Most of the time astronomers observe the universe using telescopes on Earth. These work really well, but there\u2019s a big problem with ground-based telescopes \u2013 they have to look through the Earth\u2019s atmosphere to observe the Universe.<\/p>\n
Light is electromagnetic radiation (EMR), and it comes in many different wavelengths beyond the light range that our eyes can see. You can read more about the EMR spectrum here<\/a>.<\/p>\n\n\n\n\n\n
\n At some wavelengths, light can\u2019t pass through the atmosphere at all. This can be great for us, because some wavelengths are harmful. UV radiation from the sun causes skin cancer if we don\u2019t cover up and wear sunscreen. Unlike some wavelengths of UV radiation, X-rays and gamma rays are blocked by our atmosphere. These dangerous rays can cause other types of cancer.<\/p>\n Unfortunately, this is bad for astronomy! Astronomical objects can shine in all different wavelengths, and if we can\u2019t observe them all we\u2019re missing out on important information.<\/p>\n Another problem is that the light that passes through the atmosphere gets refracted, or bent a little bit in all different directions. Bent light makes a star look like it\u2019s in a slightly different place in the sky. Since the air is always moving, the star seems to dance around, which we see as twinkling.<\/p>\n Light pollution also gets in the way of doing ground-based astronomy. This is the glow you see in the sky at night around a big city, which blocks out the stars and any faint objects.<\/p>\n Space telescopes can solve these problems by getting out above the atmosphere and into outer space. But they have lots of OTHER problems! They\u2019re expensive to launch into space, and once they\u2019re up there they can\u2019t be fixed if they have any problems. (The Hubble Space Telescope was one exception. It was serviced by NASA\u2019s space shuttle program).<\/p>\n<\/td>\n | \n |