Are we alone? Desperately looking for life in the Universe

Nidhal Guessoum

In 1600 Giordano Bruno, an Italian theologian, philosopher, and cosmologist, was burned at the stakes for insisting – among other “heresies” – that the universe contains an infinite number stars, that they are all like the Sun, and that each one is circled by planets inhabited by intelligent beings like ourselves. At the end of the 19^th century, the city of Rome erected a statue in his honor, and by the end of the 20^th century the search for other worlds, for life, and for intelligent beings had become a respectable, scientific venture.

For many centuries, the question of the existence of other worlds and other beings was a controversial question, for which the various answers given by prominent thinkers mostly reflected their own philosophical and theological biases. There was indeed no firm (scientific) knowledge for thinkers to base their views upon; things have largely changed in the past half-century or so, as we shall see.

It is interesting to review, even briefly, the history of views on the plurality of worlds. Perhaps the oldest reference we find on the question is the poetry of Orpheus, that legendary or mythical figure of around 1400 BC, who had written that the Moon is a fertile land where cities and palaces have been built (by aliens). Similar views on the Moon were expressed by the philosophers Xenophanes and Anaxagoras (ca. 5^th c. BC). It is also said that Plato believed that all planets are inhabited. Likewise, the Roman poet and philosopher Lucretius (first century BC) wrote that the heavens were full of worlds, with different peoples and animals of all kinds.

Greek philosophers of scientific inclination based their views on more rigorous arguments; for example, Pythagoras (ca. 5^th c. BC) insisted that the existence of life on other planets depended on environmental conditions, particularly the ambient temperature. Likewise Plutarch (first century AD) argued that the Moon must be sterile and virgin, for it is too hot during the day, and air there is very thin and dry, without any clouds to help…

During the Islamic era, it seems that few opinions were expressed on the question, other than attempts to interpret some Qur’anic verses that could be understood to imply the existence of other species in the cosmos, while other verses seemed to insist on the central importance of Man – hence the irrelevance of other intelligent and conscious species out there.

During the European times of renaissance and scientific revolution, strong views on the question were expressed again, especially when telescopes made it clear that the heavens were full of stars, and new planets began to be discovered. Herschel, the discoverer of Uranus, not knowing the true temperature of the Sun, thought the latter was populated by aliens. Huygens, who was the first to resolve the nature of Saturn’s rings and to discover the famous moon Titan (see my article on the search for water), believed that aliens out there resembled us…

But it was in the second half of the 20^th century that the search for extra-terrestrial (ET) life and intelligence really took on the form of a scientific question and project.

One important distinction that must always be made is between the search for “life” and the search for “intelligent species” (aliens). By “life”, scientists usually mean any organism capable of metabolizing and reproducing, no matter how small and simple it may be. Any bacteria or microbe found anywhere out there will make our day (and our year, and perhaps our century)!

The search for life

There are two ways to search for life: (a) by searching the place (“in situ”), as when we send spacecrafts to Mars and dig the ground looking for any organisms or their signatures; (b) by analyzing the environmental conditions existing in some place, from afar (“ex-situ”), as when we search for signatures of oxygen (O₂) in the atmosphere of a planet or moon, oxygen almost automatically signifying the conversion of carbon dioxide (CO₂) by plants through the photosynthesis process. Another, even more indirect way of searching for life is to look for water, especially in liquid form, as I explained in the previous article.

One of the main issues that scientists find themselves confronting when attempting to define the extra-terrestrial life they are looking for is its characteristics. Many believe that “life” everywhere must have the same basis, most likely carbon, with molecules becoming gradually more complex through chemical reactions in a favorable medium (most likely water), and with energy-based “biological” functions like metabolism and reproduction leading to the preservation and prosperity of the species. Why would life necessarily follow the exact same plan it followed here on Earth? First because Carbon is the most appropriate chemical element for forming complex molecules (it is a very “versatile” atom, which can bond with many other atoms and produce very interesting molecules), and it is one of the most abundant elements in the universe. Secondly, because water is not only ubiquitous, it has – overall – the best properties for facilitating chemical reactions and biological processes. And that is why scientists are naturally drawn to searching for other earths and for water, liquid if possible.

Other scientists point out, however, that we have found (here on Earth) places of extreme physical, chemical, and environmental conditions where life has existed and prospered for millions if not billions of years. We have found microbes and other organisms near undersea volcanoes and hydrothermal vents; such living species which can thrive in extreme conditions have been dubbed “extremophiles”.

And that is why astrobiologists have decided to take a closer look at places in the solar system that they had previously given up on, places like Mars and even Venus and moons like Europa and especially Titan. So now with strong evidence for past water on Mars, the Exomars mission is being planned for 2013. Likewise, the Titan Explorer is scheduled for launch in 2018, to arrive in 2024…

The search for intelligent species

The search for intelligent aliens took a quantum leap in 1959 (fifty years ago exactly) when Philip Morrison and Giuseppe Cocconi published a paper in the authoritative journal Nature titled “Searching for Interstellar Communications”, in which they asked themselves what would be the best method for aliens to communicate with us? In other words, what signals would they use, at which frequencies, etc.? They concluded from their analysis of various technological and astronomical factors that radio waves were best (they can travel large distances without much loss), and they focused on the wavelength of 21 cm, i.e. the frequency of 1428 MHz, which is due to hydrogen, the most common element in the universe.

The year after, 1960, Frank Drake, who was then a graduate student in radioastronomy at the same university (Cornell) as those two scientists, put together the first SETI (search for extra-terrestrial intelligence) project, named Ozma (after the wizard of Oz). Later Drake wrote a simple equation, named after him since, which attempts to estimate the number of intelligent civilizations out there; unfortunately, the equation contains several factors which are extremely difficult to pin down, and so the result is almost always something like “between 0 and millions”.

The SETI idea became very popular during the seventies, among scientists as well as the general public, with charismatic scientists like Carl Sagan taking leadership roles and writing books and novels, like Contact, famously turned into a movie with Jody Foster as the lead scientist who detects an intelligent message from out there.

By the late eighties, not only had we found no intelligent signal whatsoever, it became apparent that that with the limited technology we have (low-sensitivity dishes) and the vastness of space, the odds of getting such a signal were extremely low. In 1993, NASA pulled the plug on SETI. But soon afterwards, private funds came to the rescue, and the project started anew, though at a slower pace. The project came up with the brilliant idea of enlisting the general public to make their computers available for automatic data analysis simply by downloading a software, which would switch on whenever the computer was left idle, and link to the central database to analyze a piece of the data collected by the radio telescope. In its ten years of operation, SETI@Home, as it is called, has had close to 5.5 million participants.

Many enthusiasts have embraced SETI projects, including Paul Allen, the co-founder of Microsoft, who has donated 13.5 million dollars for building a park of radio telescopes, the first phase of which has been completed with 42 antennas; by the end of the multi-phase project, 350 antennas will be in operation. If we don’t hear any ETs by then, we can probably shut down and conclude that we are alone.

Many scientists and thinkers already believe that we are alone, at least in the Milky Way. What is their argument in the face of so many stars and planets (remember that our galaxy contains some 200 billion stars, many of which have planets)? The argument is known as the Fermi Paradox, after Enrico Fermi, one of the greatest physicists of the 20^th century, who one day discussing the prospects of the existence of intelligent aliens over lunch with his colleagues simply retorted: “where are they?” By that he meant that one can easily argue that if intelligence has developed in other places in the Galaxy, as the enthusiasts insist, then most likely one of them at least will have appeared much earlier than us, since the Galaxy is about 10 billion years old, and we as a species are less than a million years old, as a civilization only a few thousand years old, and as an “advanced” (technological) civilization only a few hundred years old. And when civilizations reach advanced levels, they certainly develop the capacity to travel in space, to reach faraway places, and to colonize planets. If there was any such species, Fermi concluded, they would have already reached here; yet we don’t see any trace of them, such as spacecrafts or listening posts in the solar system…

Sun Spot

Introduction:

Sun or Sol (in Latin), our very own star, energy from which in the form of light via photosynthesis gives and sustains life .The sun also drives the earth climate and weather. So what’s so new about this? Every small kid on this planet knows this. But sun is like any other star in our large universe .It is active and these phenomenons are called sunspots, which occur, in 11-year cycle called the solar cycle.

What is a Sun Spot?

The surface of the sun is called the photosphere .Now the sun does not have uniform temperature through out. Just like on earth there are cold regions and hot regions, there are colder and hotter regions on the sun.

So then what is a sunspot? Sunspot is a well-defined area that appear darker than the surroundings because of the lower temperature when compared to its surroundings. Sunspots will have approximate temperatures between 4000K –4500K,while the surrounding temperature will be about 5800K .So it appears dark. Now if we were to separate a sunspot from the rest of the sun, then it will brighter than an electric arc.

Inside Sunspots:

To learn this we need to know one basic term, which is convection.

Convection is basically the floe\w of currents in fluids.

So just like we have convection currents in oceans on earth, there are also convection currents in the sun. This is because convection currents are the basic mode of heat and mass transfer.

Now, the sunspots are areas of intense magnetic fields. But it is also a known fact that magnetic field of like polarities repel each other. And with observations it is also seen that surface materials flows away from the spot. There for in this area convection is inhibited or in simpler terms, magnetic field stops the normal up flow for energy from the suns hot interior to the surface. This is what makes the surface cooler and hence darker. Now according to new observation by SOHO, since the magnetic field stops the heat from being transferred, this cool matter becomes dense leading it to plunge downwards at the a speed of 3000 miles per hour. This draws the surrounding plasma and the magnetic field inwards towards the center of the sunspot. Now this concentrated field causes further cooling and hence drawing in further plasma. Thus as sun spot is like a self-perpetuating storm. The life period of any particular sunspot, with the help of observation, has been concluded as approximately two weeks.

The structure of the sunspot is as follows:

Umbra: This is the darkest part of the sunspot and here the magnetic field is nearly vertical

Penumbra: This is lighter part of the sunspot and the magnetic field in this area is slightly inclined.

As long as the magnetic field remains strong the cooling effect will maintain an inflow, which makes the structure stable. The superficial out flow seen at the surface is only present in a narrow area. Alexander Kosovichev and Junwei Zhao of Stanford University and Thomas Duvall of NASA’s Goddard Space Flight Center, Greenbelt, Md published this research August 10, 2001.

Solar Cycle, Sunspot Variation and Polarity of Sunspots:

The numbers of sunspots on the sun are never constant. But it rises and falls in an irregular cycle during a period of 11 years, which is known as the solar cycle.

The solar cycle is the dynamical engine and energy source which is behind all solar phenomena driving space weather.

Highest sunspot activity is during solar maximum of the cycle and lowest is during solar minimum of the cycle. At the start of a new solar cycle, sunspots appear in the higher latitudes of the sun and then move towards the equator as the solar cycle progress and reach the maximum. More a sunspots means, the surrounding areas are brighter and hence a brighter sun in contrary to the myth that more sunspots means a less brighter sun.

The trends for sunspots can also have longer variation like for example, the sunspots trend was upwards from 1900 to 1960 after which the cycle was downwards. There was also period known as the Little Ice Age in the 17^th century, during which sunspots on the sun became extremely rare. This is also known as the Maunder Minimum after the solar astronomer Edward Maunder who discovered it. During this period, Europe is said to have experienced colder temperatures than usual.

Sunspots also appear in Groups and come in pairs of opposite magnetic polarity. Sunspots also reverse polarity from one solar cycle to the next i.e. N-S becomes S-N and vice versa.

Space Weather & Interference With Radio Communications:

There are two major phenomenons’ that occur on the sun as a result of intense magnetic activity at the sunspot. These are the solar flares and the cornal mass ejection .To explain the two briefly:

Solar flares: Solar flares are violent explosions in the suns atmosphere releasing up to a total energy of 6 x 10^ 25 Joules. Flares are powered by sudden release of magnetic energy stored in the corona. These take place in the suns corona and chromospheres and releasing electromagnetic radiation across the electromagnetic spectrum at all wavelengths leading from long wave radio to shortest wave of gamma rays.

Coronal Mass Ejections (CME): CME is the ejection of material from the corona of the sun .The ejected material is mainly plasma consisting of electrons and protons, also includes small quantities of heavier elements such as helium, oxygen and iron and also entrained coronal magnetic field .CEM is the main reason for the appearance of auroras in the Northern and the Southern hemisphere .In the North it is known as Northern Lights or aurora borealis and in the South it is known as Southern Lights or aurora australis .

Now these two phenomenons during the solar cycle has a great effect on the space weather as well on the communication between the earth base stations and the satellites .CME events along with solar flares can disrupt radio transmissions, cause power outages in other word blackouts and cause damage to satellite and electrical transmission lines.

Solar flares also create a wide spectrum of radio noise at very high frequencies and very unsusally at high frequency. This noise may interfere directly with a wanted signal. The frequency with which a radio operator experiences solar flare effects will vary with the approximately 11-year sunspot cycle; more effects occur during solar maximum (when flare occurrence is high) than during solar minimum (when flare occurrence is very low). A radio operator can experience great difficulty in transmitting or receiving signals during solar flares due to more noise and different propagation patterns.

Observation of Sunspots:

Sunspots can be observed using land based solar telescopes as well the telescopes on satellites that are rotating in the orbit around the earth. Filtration and projection techniques are used for direct observation, as the sun should not be looked at with naked eyes or directly through a telescope. Filtered cameras of various types are used for taking photographs. Specialized equipments such as spectroscopes and spectrohelioscopes are used to observe sunspots and areas surrounding them.

Application in Studying Sunspots:

Sunspots are linked to solar activity as explained. Hence studying sunspots helps to study the space weather and in turn study the state of the ionosphere .So sunspots helps us predicting short wave radio propagation or satellite communications.

Is a New Solar Cycle About to Begin?

On December 11^th, 2007 patch magnetism appeared across the eastern limb of the sun. This has excited solar physicists greatly as they incur that this could be a beginning of a new solar cycle i.e. Solar Cycle 24

In 2007, for more than a year there was lack of activity from the sun as Solar Cycle 23 was coming to an end and Solar Minimum was up on the Solar system. But this appearance of this patch of magnetism especially in the higher latitudes of the sun and that too of reverse polarity magnetic field has brought a buzz of excitement.

Solar physicists are predicting that the Solar Cycle 24 will be big and intense. This could be a major problem for the telecommunications, air traffic, power grids and GPS but it could also put on a spectacular show in the Northern and Southern hemisphere in the form of auroras.

But still there a few years till the Solar Cycle 24 is fully developed .So let us wait for the spectacular show in the near future.

By Vidya

Major Dust Storm on Mars Visible with Backyard Telescopes By Robert Roy Britt Senior Science Writer posted: 28 October 2005 02:17 pm ET

Thanks to our member Mr. Edward Cooper for this news

Buffy the Kuiper Belt Object

Summary - (Dec 14, 2005) An international team of astronomers have discovered a new large object in the Kuiper Belt; a region of the Solar System beyond the orbit of Neptune. The object's official designation is 2004 XR 190, but the discoverers are calling it "Buffy" for now. Buffy is approximately half the size of Pluto, and orbits the Sun roughly double the distance of Neptune. Although there are larger objects in the Kuiper Belt, Buffy has one of the most unusual orbits: 47-degrees off the plane of the ecliptic, where the other planets orbit.

Full Story -

A team of astronomers working in Canada, France and the United States have discovered an unusual small body orbiting the Sun beyond Neptune, in the region astronomers call the Kuiper belt. This new object is twice as far from the Sun as Neptune and is roughly half the size of Pluto. The body's highly unusual orbit is difficult to explain using previous theories of the formation of the outer Solar System.

Currently 58 astronomical units from the Sun (1 astronomical unit, or AU, is the distance between the Earth and the Sun), the new object never approaches closer than 50 AU, because its orbit is close to circular. Almost all Kuiper belt objects discovered beyond Neptune are between 30 AU and 50 AU away. Beyond 50 AU, the main Kuiper belt appears to end, and what few objects have been discovered beyond this distance have all been on very high eccentricity (non-circular) orbits. Most of these high-eccentricity orbits are the result of Neptune "flinging" the object outward by a gravitational slingshot. However, because this new object does not approach closer than 50 AU, a different theory is needed to explain its orbit. Complicating the problem, the object's orbit also has an extreme tilt, being inclined (tilted) at 47 degrees to the rest of the Solar System.

The Discovery and Follow-up

The object, which received the official designation 2004 XR 190 in the International Astronomical Union's official announcement, was discovered during routine operation of the Canada-France Ecliptic Plane Survey (CFEPS) running as part of the Legacy Survey on the Canada France Hawaii Telescope. For now, the discoverers are using the temporary nickname "Buffy" to identify the new object, although they have proposed a different official name in keeping with normal procedures for naming such objects.

Buffy was extracted from the mountain of Legacy Survey data (about 50 gigabytes per hour of operation) by powerful computers combing through the telescopic images and producing hundreds of candidates. Astronomers then sift through the candidates to identify the distant comets.

Astronomer Lynne Allen of the University of British Columbia was the first to lay eyes on the new object, as she completed the initial identification in the course of processing CFEPS data from December 2004. "It was quite bright compared to the usual Kuiper belt objects we find", said Dr. Allen, "but what was more interesting was how far away it was."

The object's brightness implies it is likely between 500 and 1000 kilometers (300 to 600 miles) in diameter. Buffy is thus a very large Kuiper belt object, but about half a dozen are larger.

``We immediately realized that the object was about twice as far as Neptune from the Sun and that its orbit was potentially nearly circular,'' said UBC professor Brett Gladman, who noticed the unusual nature of the object when determining its orbit, ``but further observations were required.''

One to two years of observations of a Kuiper belt object are required before their orbits can be precisely measured. The first additional observations of Buffy came in October 2005 when Gladman and Phil Nicholson of Cornell University used the Hale 5-meter telescope to re-observe the object.

Measurement of Buffy's new position proved that the orbit was not only extremely tilted, inclined (tilted) at 47 degrees to the plane of the planetary system (essentially tying the record for a Kuiper belt object) but confirmed that Buffy was unlike any other previously-known object because it was on a nearly circular orbit while at a very large distance.

More measurements of Buffy's position on images from telescopes at Kitt Peak National Observatories in Arizona by team members Joel Parker (Southwest Research Institute), as well as JJ Kavelaars (National Research Council of Canada, Herzberg Institute of Astrophysics) and Wes Fraser (University of Victoria), through November 2005 refined the estimate for Buffy's closest approach to the Sun. Additional observations, to further confirm the orbit, where then provided by the CFHT Legacy Survey project. Astronomers will need to wait until February 2006 to measure the fine details of the Buffy's orbit.

The team have reported their find to the Minor Planet Center, the clearinghouse for astronomical measurements of new minor planets. "To find the first known object with a nearly circular orbit beyond 50 AU is indeed intriguing," reacted Brian Marsden, director of the MPC.

Challenging Theories

Although it is neither the smallest, largest, nor most distant object discovered in this region, the new Kuiper belt object has a highly unusual orbit which challenges theories of the evolution of the Solar System.

Why is Buffy's orbit considered so unusual? Only one other detected object, Sedna, remains further than 50 astronomical units (AUs) from the Sun throughout its entire orbit. However, Sedna is on a very elliptical orbit, swooping in to 76 AU before traveling back out beyond 900 AU. In contrast, Buffy spends all of its time in the narrow range between 52 and 62 AU from the Sun. Combined with the tilt in its orbit, this new object challenges current theories about the history of the early Solar System.

Astronomers have detected other Kuiper belt objects that spend most of their time beyond 50 AU. These are on very elliptical orbits, and almost all approach within 38 AU of the Sun. That close approach places those objects within the reach of the gravitational influence of Neptune. These objects are generally thought to have been scattered out to their present orbits by a gravitational slingshot with Neptune. This group of objects was thus called the "Scattered Disk".

Prior to the discovery of Buffy, a few other Kuiper belt objects were discovered which spend much of their time beyond 50 AU like those in the "Scattered Disk", yet did not approach within the gravitational reach of Neptune. This group has been named the "Extended Scattered Disk". Two of its members are 1995 TL8 and 2000 YW134, which approach to 40 AU of the Sun but have fairly elliptical orbits that take them back out beyond 60 AU. Two more extreme examples of the "Extended Scattered Disk" are 2000 CR105, which approaches to 44 AU, and Sedna, which never comes closer to the Sun than 76 AU.

Due to their large eccentricities, these objects are likely to have been strongly perturbed by something, although it could not have been Neptune because they do not come close enough to be scattered by that planet's gravitational force. As both Sedna and 2000 CR105 also travel beyond 500 AU from the sun, one theory is that after being scattered by Neptune, a passing star could have pulled their closest approaches away from the Sun.

Buffy is clearly a member of the "Extended Scattered Disk". However, Buffy's almost circular orbit makes it stand out from the other members. In addition, Buffy's large orbital tilt is not so easily explained by the passing star idea. If a star could have affected Buffy so strongly, it should also have disrupted much of the main Kuiper belt as well. Since astronomers do not detect that strong disruption, a more complex theory is needed to explain Buffy's orbit.

The elusive explanation may lie in side-effects from rearrangements of the Solar System early in its history. One possibility is that as Neptune's orbit slowly expanded in the young Solar System, complex gravitational interactions could have caused some Kuiper belt orbits to circularize and tilt. While Buffy's orbit could have been created this way, this theory would not seem to explain 2000 CR105 and Sedna. This new discovery is exciting because it causes us to rethink our understanding of how the Kuiper belt formed.

The Future

Over the last half decade, theories about the formation of our outer Solar System have been pushed to their limits: unusual Kuiper belt objects, like Buffy, which never come close to Neptune yet have high inclination must be explained.

Although theories that explain individual objects exist, reproducing the entire ensemble of known objects with one process poses a difficult challenge to current solar system models. Because the unusual objects, like Buffy, are very rare, astronomers are still scratching the surface of the dark corners of the Kuiper belt. Future large-scale surveys that systematically explore the Kuiper belt are the only way unlock the mysteries of what happened early in the history of our Solar System.

Original Source: Canada-France-Hawaii Telescope

10th Planet has a Moon

Summary - (Oct 3, 2005) The newly discovered 10th planet - which the discoverers have dubbed "Xena" - appears to have a moon of its own. Nicknamed "Gabrielle", this moon is 100 times fainter than Xena, and seems to orbit the planet once every couple of weeks. It's estimated to be 1/10th the size of Xena, so approximately 250 km (155 miles) across. The powerful Hubble Space Telescope will be turning its gaze on the pair in November/December, and should reveal even more details.

Full Story -

The newly discovered 10th planet, 2003 UB313, is looking more and more like one of the solar system's major players. It has the heft of a real planet (latest estimates put it at about 20 percent larger than Pluto), a catchy code name (Xena, after the TV warrior princess), and a Guinness Book-ish record of its own (at about 97 astronomical units-or 9 billion miles from the sun-it is the solar system's farthest detected object). And, astronomers from the California Institute of Technology and their colleagues have now discovered, it has a moon.

The moon, 100 times fainter than Xena and orbiting the planet once every couple of weeks, was spotted on September 10, 2005, with the 10-meter Keck II telescope at the W.M. Keck Observatory in Hawaii by Michael E. Brown, professor of planetary astronomy, and his colleagues at Caltech, the Keck Observatory, Yale University, and the Gemini Observatory in Hawaii. The research was partly funded by NASA. A paper about the discovery was submitted on October 3 to Astrophysical Journal Letters.

"Since the day we discovered Xena, the big question has been whether or not it has a moon," says Brown. "Having a moon is just inherently cool-and it is something that most self-respecting planets have, so it is good to see that this one does too."

Brown estimates that the moon, nicknamed "Gabrielle"-after the fictional Xena's fictional sidekick-is at least one-tenth of the size of Xena, which is thought to be about 2700 km in diameter (Pluto is 2274 km), and may be around 250 km across.

To know Gabrielle's size more precisely, the researchers need to know the moon's composition, which has not yet been determined. Most objects in the Kuiper Belt, the massive swath of miniplanets that stretches from beyond Neptune out into the distant fringes of the solar system, are about half rock and half water ice. Since a half-rock, half-ice surface reflects a fairly predictable amount of sunlight, a general estimate of the size of an object with that composition can be made. Very icy objects, however, reflect a lot more light, and so will appear brighter-and thus bigger-than similarly sized rocky objects.

Further observations of the moon with NASA's Hubble Space Telescope, planned for November and December, will allow Brown and his colleagues to pin down Gabrielle's exact orbit around Xena. With that data, they will be able to calculate Xena's mass, using a formula first devised some 300 years ago by Isaac Newton.

"A combination of the distance of the moon from the planet and the speed it goes around the planet tells you very precisely what the mass of the planet is," explains Brown. "If the planet is very massive, the moon will go around very fast; if it is less massive, the moon will travel more slowly. It is the only way we could ever measure the mass of Xena-because it has a moon."

The researchers discovered Gabrielle using Keck II's recently commissioned Laser Guide Star Adaptive Optics system. Adaptive optics is a technique that removes the blurring of atmospheric turbulence, creating images as sharp as would be obtained from space-based telescopes. The new laser guide star system allows researchers to create an artificial "star" by bouncing a laser beam off a layer of the atmosphere about 75 miles above the ground. Bright stars located near the object of interest are used as the reference point for the adaptive optics corrections. Since no bright stars are naturally found near Xena, adaptive optics imaging would have been impossible without the laser system.

"With Laser Guide Star Adaptive Optics, observers not only get more resolution, but the light from distant objects is concentrated over a much smaller area of the sky, making faint detections possible," says Marcos van Dam, adaptive optics scientist at the W.M. Keck Observatory, and second author on the new paper.

The new system also allowed Brown and his colleagues to observe a small moon in January around 2003 EL61, code-named "Santa," another large new Kuiper Belt object. No moon was spotted around 2005 FY9-or "Easterbunny"-the third of the three big Kuiper Belt objects recently discovered by Brown and his colleagues using the 48-inch Samuel Oschin Telescope at Palomar Observatory. But the presence of moons around three of the Kuiper Belt's four largest objects-Xena, Santa, and Pluto-challenges conventional ideas about how worlds in this region of the solar system acquire satellites.

Previously, researchers believed that Kuiper Belt objects obtained moons through a process called gravitational capture, in which two formerly separate objects moved too close to one another and become entrapped in each other's gravitational embrace. This was thought to be true of the Kuiper Belt's small denizens-but not, however, of Pluto. Pluto's massive, closely orbiting moon, Charon, broke off the planet billions of years ago, after it was smashed by another Kuiper Belt object. Xena's and Santa's moons appear best explained by a similar origin.

"Pluto once seemed a unique oddball at the fringe of the solar system," Brown says. "But we now see that Xena, Pluto, and the others are part of a diverse family of large objects with similar characteristics, histories, and even moons, which together will teach us much more about the solar system than any single oddball ever would."

Original Source: Caltech News Release

Astrophotography for Beginners

by Dave Martin, skyhawk1@pcisys.net

Have you ever wanted to try taking astrophotos but have not been sure where to start? What type of film should you use? What type of camera is needed? How long of an exposure should you use? If you answered yes to any of these questions, then this article is for you. I’ll discuss what to look for in a camera, what films work well and some of the equipment and techniques used in basic astrophotography.

Camera
To take photographs, you need a camera. Of the many types available, 35mm Single Lens Reflex cameras are best suited for beginning astrophotography. They are readily available, have all the desirable features and 35mm film is offered in a very wide range of types. Modern cameras are marvels of mechanical, optical and electronic ingenuity with automatic exposure control, automatic focusing and many other features. However, astrophotography has special demands that most modern cameras cannot cope with. This is one place where automatic features of a camera are not desirable and the older fully manual cameras are better suited.

Features you do not want in a camera are automatic focus and automatic exposure control. Both of these are designed for typical snapshot photography and are not needed or useful for astrophotography. The majority of new cameras being sold today are the fully automatic types that are completely dependent on battery power. Fortunately, as photographers upgrade to a newer camera, they often sell or trade in their older, manual cameras. These used manual cameras may be found at camera repair shops, flea markets and pawn shops. Camera bodies with broken light meters or inaccurate shutter speeds can often be found quite cheaply and may be perfect for astrophotography.

The first feature a camera must have is a mechanical bulb or time setting to allow it to take long duration exposures. Many newer cameras use a solenoid to operate the shutter and will not work if the batteries are removed or dead. Even if the camera has a time setting, the long exposure times will quickly drain the batteries. Mechanical shutters do not rely on batteries and can take the long exposures necessary.

The other essential feature is interchangeable lenses. These allow you to change the magnification of the photo from a low power wide angle shot to a high power close up of the object being photographed. With appropriate adapters, the camera body may be attached directly to a telescope so that the telescope becomes a super telephoto lens.

Two highly desirable features in a camera are an interchangeable focusing screen and mirror lock up. In the 35mm SLR camera, the light enters the lens and is reflected upwards to form an image onto a small glass or plastic focusing screen. This image is then reflected by a prism so it can be seen in the camera viewfinder. Standard focusing screens are designed for typical daylight use with relatively short focal length lenses. At night or when using very long focal length lenses, the images formed on standard focusing screens may be dim and hard to see. Some cameras allow the focusing screen to be replaced with special focusing screens specifically for astrophotography. The images formed by these specialty screens are much brighter and easier to see and focus with. Replacement focusing screens can be expensive but after using one, you won’t want to use a standard focusing screen again. Aside from their cost, the disadvantage of these focusing screens is that they can cause the light meter to read incorrectly. The screen must be replaced with a regular screen when using the camera for regular photography.

At the high magnifications often used in astrophotography, small vibrations can be magnified to giant blurs on the film. Mirror lock up is a useful feature to reduce some of these vibrations. In a SLR camera, a small mirror hangs down in the light path to divert the incoming light to the focusing screen and on to the viewfinder. When the shutter is tripped, the mirror has to move out of the light path to allow the light to strike the film. When the mirror moves, it hits limit stops which may create vibrations that become visible blurs in the photograph. Some cameras have a lever or button to move the mirror before the shutter is tripped. This greatly reduces at least one source of vibrations that can ruin your photograph. Canon, Nikon, Pentax, Olympus and others have manufactured cameras with ideal features for astrophotography. Some of the more popular models are the Canon F-1, Nikon F, Nikon F2, Pentax LX and the Olympus OM-1, OM-2, OM-3 and OM-4 models. The Olympus OM-1 has long been popular for astrophotography as it combines all of the features listed above at a reasonable cost.

Lenses
To go along with the camera body, you should have a couple of lenses to use with it. Camera lenses have two important specifications. First is the focal length in millimeters, such as 50mm or 135mm. The focal length is what determines the image size or magnification of a lens. Unlike in telescopes where you use shorter focal length eyepieces to increase magnification, in cameras the longer the focal length, the higher the magnification. The longer the focal length of a lens, the larger the image on the film will be.

For example, if you take a photo of the moon or Jupiter with a 35mm camera, the image size in millimeters on the negative would be:

Barn Door Mounts
OK, you want to take longer exposures without star trails and without spending a lot of money to do it? The answer is a Barn Door mount, also known as a Scotch or Haig mount. This is little more than two boards and a hinge. The bottom board is held stationary while a camera is attached to the moveable top board. The axis of the hinge is aligned with the celestial pole and a threaded rod is rotated to force the top board to move. This movement counteracts the rotation of the Earth and allows the camera to remain fixed relative to the stars.

With the correct dimensions of the boards and the rod, a barn door drive is suitable for exposures of up to ten minutes. Not bad for a few dollars worth of materials! More elaborate versions of barn door mounts have been made with motor drives, multiple hinges and guide scopes. Some of these are capable of accurately tracking the stars for up to thirty minutes. Plans for making barn door mounts are available in many astronomy books and on the world wide web.

Afocal Projection
The next level up is afocal projection. The camera is fitted with a normal lens and attached to a tripod. The camera lens is then placed as close as possible to the eyepiece of a telescope and then focused on the image formed by the eyepiece. This yields much greater magnification than using a camera lens alone. This increased magnification significantly limits the exposure time before blurring begins however. Surprisingly good results may be obtained if care is taken to focus well and if stray light is prevented from entering the camera lens.

For longer afocal exposures, the camera can be mounted to a motorized telescope. To calculate the overall focal length of an afocal projection setup, multiply the magnification of the telescope and eyepiece combination by the focal length of the camera lens. For example; using a telescope with a focal length of 2000mm and a 32mm eyepiece produces a magnification of 2000 / 32 = 63x. Using a 50mm lens on a camera produces an effective focal length of 63 / 50 = 3125 mm. The f-ratio of this setup is the effective focal length divided by the telescope lens or mirror diameter. By using the example above, an 8 inch or 200mm scope is 3125 / 200 = 15.6 f-ratio.

Piggyback Mounts
When a camera and a normal lens is attached to a telescope or other moveable platform, the technique is called piggyback mounting. In this case, the camera goes along for the ride while the telescope tracks the stars. With a motorized telescope, very long exposures may be taken using a piggyback mount. While piggyback mounting is normally done with a motorized telescope, beautiful astrophotos have been taken by piggyback mounting a camera to a Dobsonian telescope and then manually guiding the telescope for up to thirty minutes. This method requires large amounts of patience. A camera and tripod can be set on a motorized equatorial platform for exposures of several minutes.

Prime Focus
Moving up in difficulty is prime focus. This is where the camera is attached directly to the telescope so that the image formed by the telescope optics falls directly on the film. The basic hardware to attach the camera is called a tele-extender which is nothing more than a fancy name for a hollow tube. The tele-extender attaches to the telescope, either by fitting into the focuser or by threading onto the back of a Schmidt-Cassegrain telescope.

The other end of the tele-extender is threaded to attach a T-Ring adapter. T-Rings are available for most cameras and are necessary to attach the camera to the tele-extender. By changing the T-ring, many different cameras can be used with the tele-extender or other accessories. Obtaining successful prime focus astrophotos depends a great deal on the accuracy of the polar alignment of the telescope, the accuracy of the drive motors and the duration of the exposure. For prime focus photography, the focal length and f-ratio of the telescope are used to calculate exposure times.

Guiding
A variant of prime focus is guided exposures. If the telescope drive has a controller to adjust tracking, then long duration photos may be taken by correcting tracking errors during the exposure. Guiding can be done with a separate telescope mounted to the main telescope or device called a radial guider may be used. This device attaches to the telescope and has threads for a T-Ring to attach a camera, same as the tele-extender. In the radial guider a small prism projects slightly into the light path. The prism diverts a small amount of light to an eyepiece at a right angle to the light path.

After aligning and focusing the telescope and camera on the object to be photographed, the guide scope or prism is adjusted so that a bright guide star is visible in the guiding eyepiece. The eyepiece used normally has an illuminated reticule or crosshairs. For the duration of the exposure, the tracking of the telescope is adjusted with the controller to keep the guide star centered on the cross hairs of the guiding eyepiece.

For long exposures, this can be an extremely tedious process. Many astrophotographers now use a specialized CCD camera called an autoguider to take their photographs. The CCD tracks the guide star and adjusts the telescope tracking automatically. After the first few minutes of manually guiding a long exposure, a CCD autoguider may begin to seem like a necessity rather than a luxury.

Eyepiece Projection
The most difficult form of astrophotography is called eyepiece projection. The difficulty is due to the very long focal lengths and large f-ratios involved. These demand a high degree of tracking precision and freedom from vibration to capture a sharp image on film.

Eyepiece projection uses the same tele-extender tube used for prime focus astrophotography but now an eyepiece is fitted inside the tube. The camera is then focused on the image produced by the eyepiece. The combination of telescope and eyepiece create a very long effective focal length and magnification.

To calculate the focal length and focal ratio, you must first determine the magnification factor. First, measure the distance from the eyepiece lens to the film plane in the camera. Subtract the focal length of the eyepiece from this distance. Divide this value by the focal length of the eyepiece to yield magnification. By using the example above and an eyepiece to film distance of 110 millimeters results in: (110 - 32) /32 = 2.4x magnification (over prime focus), 2.4 x 2000 (focal length of telescope) = 4875 millimeters focal length, 4875 / 200 (telescope aperture) = 24.3 focal ratio.

Replacing the 32mm eyepiece with an 11mm eyepiece, these numbers shoot up to magnification = 12, focal length = 24,545 mm and f-ratio is 122.7.

Accessories
Most hobbies require a few accessories to get the most out of them and astrophotography is no different. A must have accessory is a locking shutter release cable. This is what keeps the camera shutter open for those long exposures. Get a long cable as they transfer less vibration to the camera than shorter cables. Things to look for in a cable release are flexibility in the cold and ease of use, especially when wearing gloves.

For shorter exposures, especially when doing eyepiece projection, an air bulb shutter release is very nice to have. Using a long vinyl tube with an air bulb and a pneumatic plunger to trip the shutter, they transmit very little vibration to the camera.

A timer to track the exposure times is necessary. In a pinch, exposures can be timed by counting one one thousand, two one thousand, that’s not a very accurate method. A watch can be used but having to check it often is not very convenient. Many electronic countdown timers are available that are almost perfect for timing astrophotos. The desired exposure time is entered into the timer and a start button is pressed. A beep or buzzer indicates the end of the exposure time. Simple, accurate and convenient. Suitable timers are available from Radio Shack and other electronics stores at reasonable cost.

A notebook is a must have item. Faithfully record all details about each exposure, writing down the subject, date, time, lens used, exposure time and any other relevant notes. Reference these notes as a starting point for the next round of exposures. Without reference notes, you are shooting blind each time you go out. More convenient in the field but more work when transcribing notes is a small cassette recorder. Just speak the information into the recorder.

Some cameras have an attachment that fits over the viewfinder to form a right angle viewfinder. These devices make focusing of the camera much easier, especially when photographing objects high overhead. When using a camera in conjunction with a telescope, a simple focusing aid is to cut two holes in cardboard or other suitable material to form an aperture mask. When placed over the objective of the telescope, it creates two images. As the telescope is focused, the images will move. When they overlap, the telescope is perfectly focused.
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There are many books, magazine articles, and web sites on astrophotography. Sky and Telescope and Astronomy magazines run frequent articles on various aspects of astrophotography ranging from how to choose a camera to reviews of the latest films. The image galleries can provide starting points for exposure times and lenses to use.

Often a local library or used bookstore may have books on astrophotography ranging from simple introductions to advanced texts. An excellent book for astrophotographers of all levels is Michael Covington’s Astrophotography for the Amateur. Much of the information for this article came from this book. All of the topics in this article are covered in much greater detail in the book. It also has examples of the necessary math to calculate focal ratios, exposure times and much more.

Astrophotography–An Introduction by H. J. P. Arnold also covers the topics discussed here in greater detail. A recently published book for beginning astrophotographers is Splendors of the Universe by Terence Dickinson and Jack Newton. While its coverage of technical details is limited, this book is full of beautiful astrophotos, many taken with simple equipment.