Saturday, December 5, 2009

What's Up? Telescope Giants of the Future

Welcome back to What's Up?

Last month, the new Herschel space telescope "fingerprinted" the largest known star, VY Canis Majoris. VY Canis Majoris is so huge that if it was placed in the solar system, the surface of the star would be beyond Saturn's orbit!

Spectral fingerprinting is what astronomers use to tell what something is made of. To do this, light is split up into its different colours, creating a rainbow. In the rainbow are thin dark gaps of certain colours. These gaps are very specific to certain atoms or molecules.

In the case of VY Canis Majoris, astronomers noted something startling. The different atoms and molecules detected coming from the star indicate that the star is ready to explode at any moment. This could be minutes from now, or thousands of years from now, nobody knows. 

This discovery comes only months after launching the Herschel telescope into space. It is an infrared (a type of light that you can feel as heat) telescope with a mirror width of 3.5 meters (11 feet) and is the largest telescope of its kind.

Many enormous new telescopes are currently being designed, but are very costly so only a few will be built. Some of these will be much larger than a tennis court! Why on Earth, would anyone want to make such a big telescope?

With your eyes, which are about half a centimetre in diameter (a quarter of an inch), you collect only a small amount of light particles (photons) when it's dark. With a large telescope you can collect a much larger number of photons. Think about it as the difference between collecting rain with a spoon and a bucket. The larger the light bucket - the telescope - the more photons you can collect and the fainter the objects you can see.

The largest optical telescope (observes light our eyes can see) is just over 10 meters in diameter (34 feet) and is situated on a mountain in the Canary Islands.

Even larger and more powerful telescopes are already in the works.

The Hubble space telescope has served astronomers well over the last two decades but is wearing out. Scheduled to "replace" the Hubble is the James Webb space telescope.

The James Webb space telescope is a massive infrared observatory. It is so big that its main mirror can't fit into the biggest rockets, so it will be cut into smaller pieces. Its mirror will be 6.5 meters in diameter (20 feet) and will be made of 18 segments that will unfold in space.

The James Webb will observe the formation of the first stars and galaxies billions of years ago, as well as being able to image large planets orbiting other stars.

The reason for sending telescopes into space is to get away from the atmosphere, which blurs and distorts the images.

A new technology to help Earth-based telescopes see clearly, called adaptive optics, changes the shape of the mirror thousands of times per second to correct for the Earth's annoying atmosphere.

At the moment, there are a few very large telescopes being designed, which could be many tens of meters in diameter. One of these is already in the final planning stages and is expected to be finished by 2018.

This telescope is creatively named the Extremely Large Telescope. Its mirror will span 42 meters (140 feet) and is expected to be 100 times as powerful as the Hubble telescope.

With this mirror it will be able to image the the closest extrasolar planets and resolve stars in many other galaxies. Using the spectral fingerprinting technique, it will be able to see how shifted to the red the colours in other galaxies are to tell us how fast those galaxies are moving away from us. It will even be able to see the redshift change over time as the expansion of the universe slowly accelerates!

There was another very large telescope planned, called the Overwhelmingly Large Telescope, but was scrapped because it was too expensive and too difficult to build. It would have been 100 meters (330 feet) in diameter and would have been able to regularly observe objects 1500 times dimmer than the faintest objects the Hubble telescope has seen.

It would even be able to get the spectral fingerprint of Earth-sized planets that could be around the 40 nearest sun-like stars! The spectral fingerprinting could be used to look for certain molecules that can only be created by life.

Maybe someday the Overwhelmingly Large Telescope will gaze upon the skies, but for now, let's see what's up this month.

On Dec. 2 the Moon was full and will become a New Moon again by Dec. 16. There is a second full moon this month, the "blue moon," on Dec. 31.

The Geminid meteor shower will be best later on the night of Dec. 13 or very early (about 3 a.m.) on Dec. 14. You can expect to see up to 60 multi-coloured meteors (shooting stars) per hour.

On Dec. 21 will be the Winter Solstice, the shortest day of the year (or the longest night if you want to look on the bright side). This is also considered the first day of winter, the season with the clearest and darkest skies.

The Athena Community Astronomy Club will be having its Christmas party on Sunday, Dec. 13 from 7pm to 9pm at the YMCA on Green's street.

Until next month, just look up!

Hey Kids...
Last month, new findings of the possibility of bacteria in a meteorite from Mars was published. The meteorite in question, is a large hunk of rock that was blasted off Mars during a big impact millions of years ago. In 1996 some scientists saw what looked like fossilized bacteria, almost like tiny fossilized worms. With new scientific instruments some interesting features were discovered. The material that the fossils are made out of is magnetite, a type of magnetic rock that is created by some kinds of bacteria. The way the magnetite was formed also looks like the way bacteria would leave it behind. Who knows, maybe it is the remains of life from Mars?