When you look up at the night sky, what you see is only a tiny fraction of what is actually out there, and what you see depends on how you look. If you look with a telescope you’re going to see far more detail than with the unaided eye, and if you use a very powerful telescope that is beyond Earth’s obscuring atmosphere, such as the Hubble, you’re going to see so much more. Because the universe is so vast and distances between objects in space are so enormous, it’s difficult to see detail even with state of the art equipment. Although light travels at the tremendously fast speed of 186,282 miles per second, it still takes billions of years for light from objects at the edge of the universe to reach our eyes here on earth, so what you see is the way the objects looked billions of years ago rather than the way they look today.
What you see also depends on the type of radiation detected by the telescope you’re using. Light is made up of electromagnetic waves, and the length of these waves determines the color we see. You can imagine this length as the distance between the crests of waves in the ocean. Our eyes can only detect electromagnetic radiation within a certain range of wavelengths, what we call the visible spectrum, but objects on Earth and in space also emit radiation of longer and shorter wavelengths that we cannot see. Radio waves, microwaves and infrared have longer wavelengths than visible light, while ultraviolet, X-Rays and gamma rays have shorter wavelengths. Telescopes have been built that detect these other types of radiation and convert them into visible images which show a very different picture from that of visible light.
Radio telescopes, for example, detect radio waves. They are used to study solar flares and sunspots, thus providing advance warning of dangerous solar flares that can disrupt radio communication on earth. Radio waves can penetrate the clouds in the atmospheres of planets, and are used to measure surface temperatures of planets and moons in our Solar System. Radio telescopes also allow the detection of a range of chemicals on celestial objects. These include water vapor, ammonia, ethanol and carbon dioxide. Radio astronomy enables us to observe the Cosmic Microwave Background Radiation which is the radiation remaining from the birth of the Universe in the Big Bang. It allows us to explore the era before the first stars and galaxies were formed, and to study the first generation of galaxies. Since radio waves can penetrate dust clouds, radio telescopes are used to study the dust-filled environments where stars and planets are born as well as the center of our Galaxy, the Milky Way. They also enable us to detect the black holes at the heart of most galaxies.
Advanced technologies such as radio, gamma ray and infrared telescopes have opened new windows on our universe, creating new ways of seeing. One can only wonder what still lies ahead!
If you’re in the mood for stargazing, consider attending Arunah Hill Days at the Arunah Hill Natural Science Center in Cummington from September 2nd to 5th. This free family-oriented weekend includes stargazing, nature walks, GPS treasure hunts, rocket building, launching, and science education. Friday night features talks by young scientists. Tyler Faits presents “Seeing at Night: Physiology of Vision,” and Kate Lonergan presents “Ready for my Close Up: Seeing Saturn through Cassini’s Eyes.” On Saturday night, Professor Steve Schnieder speaks on “Galaxy Formation throughout Time: from Hubble to the Large Millimeter Telescope.” Professor Schneider is head of the University of Massachusetts Astronomy Department. For more information, visit www.arunah.org.
Copyright © Amanda Jermyn