Interferometry is a technique that is used today with both optical and radio telescopes. They can use it to zero in on very small areas of the sky, like individual stars or the centers of galaxies. When multiple telescopes (A and B) are combined in an interferometer, the resulting super-observatory lets astronomers achieve the sharpness of a much larger telescope (C). The distance an object travels, he calculated, is. Through his experiments, Galileo countered the pervasive Aristotelian view, which held that heavier objects fall faster than lighter objects. It states that objects fall at the same speed regardless of weight or shape. If this isn’t possible, they combine light from two or more telescopes in a technique called interferometry, as with the Crab Nebula radio image. The law of falling bodies is one of Galileos key contributions to physics. To get clearer views of objects, astronomers want to build ever-larger telescopes. Even a large telescope may not provide a sharp enough view. Sometimes a target is too far away or is one of many objects in a crowded field. The resulting image looks clearer and sharper, as if the atmosphere weren’t in the way. Information is then fed to a mechanism that makes constant, tiny adjustments to the mirrors to match the atmospheric distortion. This creates an artificial “guide star” that the system uses to measure the distortion of our atmosphere. The Result of Adaptive OpticsĪn adaptive optics system shoots a laser beam through the atmosphere. There are two ways to deal with this atmospheric blurring: put observatories in space above the atmosphere or add adaptive optics to telescopes on the ground.Īdaptive optics systems distort mirrors to “correct” for atmospheric effects. While Earth’s atmosphere makes life possible, it also gets in the way of astronomers who want to study objects in space. Seeing Through Earth’s Turbulent Atmosphere How Adaptive Optics Systems Work These spectral “fingerprints” help identify many physical characteristics of stars, planets, and galaxies. Observing them over several nights, he noted that they. 7, 1610, Italian astronomer Galileo Galilei noticed three other points of light near the planet, at first believing them to be distant stars. Peering through his newly-improved 20-power homemade telescope at the planet Jupiter on Jan. The way the dark and light bars are arranged in a spectrum can also reveal the speed of an object and the direction in which it is moving. 410 Years Ago: Galileo Discovers Jupiter’s Moons. What a Spectrum Tells UsĪ spectrum of the light from an object indicates its temperature and the chemical elements it contains. Their tools are spectrographs and spectroscopes, which break up light into its component wavelengths. Today, astronomers study all the light streaming from objects in space. This visible light is just a small part of the electromagnetic spectrum. If you send sunlight through a prism, as Sir Isaac Newton did, you’ll see a rainbow of colors.
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