Reach for the Stars… September 2011
In last month’s column we looked at how the type of radiation detected by the telescope you’re using affects what you see. We saw that telescopes have been designed to detect radiation with both longer and shorter wavelengths than visible light, creating fresh ways of viewing the wonders of our universe.
Ultraviolet telescopes, for example, are used to detect ultraviolet radiation from the sun and other stars. The largest such telescope is the Extreme Ultraviolet Imaging Telescope, housed in the Solar and Heliospheric Observatory (SOHO) spacecraft located above Earth’s obscuring atmosphere. It is used to study the structure and make up of the Sun’s corona (its atmosphere) which is hard to view in visible light.
Infrared telescopes can be used to track objects in space because most celestial bodies emit infrared radiation. Because these telescopes can penetrate dust and gas far better than those using visible light, they can observe dim, relatively cool objects, and can provide copious information about the object being observed. For instance, weather satellites observe Earth from space in infrared, providing information on its temperature and heat distribution. The Hubble Space Telescope, with an infrared upgrade, is now able to see far more stars, and in far greater detail than before. In 2005 the Spitzer Space Telescope became the first telescope to directly capture infrared light from planets outside our solar system. Previously, the existence of such exoplanets had only been indirectly inferred from the change in brightness created as the planet passes in front of its star or from its effects on the star’s gravity. The James Webb Space Telescope, the new infrared telescope currently in production, will study the birth and evolution of galaxies, and the formation of stars and exoplanets. It aims to observe some of the most distant objects in the universe, including the very first stars. Closer to home, it hopes to study shifting temperature patterns at Neptune’s poles. Unfortunately the future of this mission is currently under review for cancellation by Congress as a cost-saving measure.
Since the Earth’s atmosphere absorbs most X-rays, telescopes designed to detect X-rays need to be space-based. The Chandra X-Ray Observatory, a satellite launched in 1999, is one of NASA’s major observatories, charged with elucidating the structure and evolution of the universe. Chandra has been responsible for an amazing array of discoveries, including X-ray images of the supermassive black hole at the center of the Milky Way and X-ray images of the shock wave of a supernova explosion. It has also found strong evidence that dark matter exists by observing collisions of superclusters of galaxies.
Another space-based telescope, the Swift, is designed to detect gamma-ray bursts in gamma-ray, X-ray, ultraviolet and visible light wavelengths. Gamma-ray bursts are emitted by black holes and during the collapse of extremely massive stars. Earlier this year, Swift detected bursts indicating that a star 4.5 billion light years away was being torn apart after wandering too close to a black hole.
We’ve come a long way since Galileo’s first telescopes. At the time the best humanity could do was observe a small match from across a football field. Today we can do much better; we can see a match from across the country! Galileo’s new and wondrous instruments, however, were no less revolutionary for their time.
This month, join the Springfield STARS Club on Tuesday, September 27th at 7.30pm at the Springfield Science Museum for a report back on this summer’s star parties – Stellafane, The Conjunction, Arunah Hill Days and Music and Astronomy under the Stars, held at Tanglewood. Refreshments will be served, and the public is welcome free of charge.
Copyright © Amanda Jermyn