Observing the Universe Scientists use a number of
Observing the Universe Scientists use a number of instruments to study various properties of the universe. Tools for Studying the Universe ● ● spectroscopes telescopes satellites probes
Spectroscopes A spectroscope helps us find out what stars are made of by dispersing or separating white light from a star into a very wide spectrum of colors. Electromagnetic radiation interacts with objects and materials in different ways. But each material tends to behave consistently in terms of which types of radiation it absorbs, reflects, or emits (gives off). When a material absorbs or emits a unique set of different colors of visible light, the characteristic set of color bands observed through a spectroscope is the material's spectrum. Since scientists know the characteristic spectra of different materials present here on Earth, they can compare these spectra to others obtained by viewing distant objects in space through a spectroscope. Just by looking at the spectra of glowing objects such as galaxies, stars, and nebula, scientists can tell what they are made of.
Telescopes can help astronomers gather information about distant objects, including what they are made of, how fast they are moving towards or away from Earth, and even what temperature they are. Some telescopes are set up on the ground. Others are placed on satellites that transmit data back to Earth. These space-based telescopes can gather better data because there is no interference from Earth's atmosphere. Different kinds of telescopes are designed to observe different parts of the electromagnetic (EM) spectrum. Because different wavelengths of light are produced and blocked by different things, each telescope can reveal unique parts of the universe. ● ● ● X-ray telescopes are used to examine the x-ray radiation that comes from different objects. They cannot travel far through the Earth's atmosphere. X-rays are produced by many high-energy objects in space. Light telescopes are tools used to examine objects using light in or near the visible range. These telescopes allow people to see the objects as they would if they were much closer to the objects. Radio telescopes are used to examine the radio waves that come from different objects. Radio waves are not easily scattered, so they can travel long distances. Ground-based radio telescopes can collect data during the day or night and in any weather conditions.
Satellites A satellite is an unmanned spacecraft that is put into orbit around the Earth. Satellites have become very common over the past two decades, and there are currently about 5, 000 satellites orbiting the Earth. Most of these 5, 000 satellites run on solar power, but a few run on nuclear power. Some of the technologies that depend on satellites are cellular phones, global positioning systems, and weather tracking systems that can track weather on a global scale. There also many satellites in orbit around the Earth that are meant to help study the universe. Some of these satellites are telescopes, the most famous of which is the Hubble Space Telescope.
Probes A probe is an unmanned spacecraft carrying instruments intended for use in exploration of the physical properties of celestial bodies other than Earth. It is launched with enough energy to escape the gravitational field of Earth. Probes have traveled further than any other man-made object in history. As a matter of fact, multiple probes have left our solar system. Much of the information we have about the other planets and moons in our solar system actually came from probes. Every planet in our solar system has been closely observed by a space probe. Space probes have the ability to examine many properties of planets and moons. They can examine atmospheres, weather, magnetic fields, surface features, and many other features of planets and moons. Some probes have actually entered the atmosphere of other planets. We have sent probes into the atmospheres of Venus, Mars, and Jupiter.
To help get a more complete picture of our universe, NASA has developed a set of observatories that gather data using radiation in different regions of the electromagnetic spectrum. NASA's four Great Observatories, shown below, were intended to produce images of, and collect data from, our universe using four different types of electromagnetic radiation. The Great Observatories in order of launch date are: 1. The Hubble Space Telescope 2. The Compton Gamma Ray Observatory 3. The Chandra X-ray Observatory 4. The Spitzer Space Telescope.
Hubble Space Telescope The Hubble Space Telescope was the first of the Great Observatories to be launched into orbit. Named after scientist Edwin Hubble. It began its service in 1990, but gained its full capability in 1993. Hubble uses light in the infrared, visible, and ultraviolet ranges of the electromagnetic spectrum to produce images of space objects and send them back to Earth. The Hubble Space Telescope is credited with helping scientists to discover the age of the universe.
- Slides: 7