Optical Telescopes, Radio Telescopes and Other Technologies Advance Our Understanding of Space Unit E: Topic Three

3.2 Using Technology to See Beyond the Visible http://www.youtube.com/watch?v=pWlukTTVavg

Electromagnetic Spectrum All the different types of energy can be plotted on a spectrum based on their wavelengths and frequencies. Visible light is the only frequency that our eyes can pick up. Technology can pick up the rest.

The Use of Space Probes Unmanned satellites or remote-controlled “landers” that put equipment on or close to planets where it would be too difficult or dangerous to send humans. They gather data and send it back to earth. They are used to understand as much of Mars as possible before the next great adventure of taking a 3 year manned trip there. http://education.nationalgeographic.com/education/activity/space-probes/?ar_a=1

Radio Telescopes Purpose: Incoming signals are used to map out the composition and distribution of matter in space. Radio waves are received from stars, galaxies, nebulae, the Sun, and even some planets – both in our own solar system and in others. Limitation: Must be very large to attain great resolution. Found in Puerto Rico – the diameter Is the length of 3 football fields.

Listening to the sky Karl Jansky discovered radio waves coming from the Milky Way galaxy in 1931. MANY astronomers built radio dishes (telescopes) to listen to the sky. Some places in the sky would give of stronger radio waves than others so he decided there must be radio objects in space. Radio Telescopes work just as well through clouds as they do when it is clear skies! COOL!

Resolving power Wavelength impacts resolving power too. Visible light has a short wavelength – the smaller the wavelength the better the resolving power. Radio waves have a MUCH LARGER wavelength than visible light so the details picked up in space are not very good. BUT! Radio waves can travel through dust and gas undisturbed whereas visible light cannot. This tells us SOOO much more about things in space.

Advantages of Radio Telescopes http://www.youtube.com/watch?v=sAlrKptnD4Q Radio telescopes are not affected by weather, clouds, pollution or atmosphere Radio waves can be detected day and night. Images that cannot be collected by optical equipment can be detected by radio telescopes.

Visible light Image of Centaurus A (Radio Galaxy – 16 MILLION light years away) Radio Image of Centaurs A. Radio waves are recorded in a computer and then converted into color based on the strength of the radio wave. Blue is for low strength, Reds are for high.

Radio Interferometry Benefit: Offer more accuracy in measurements By arranging radio telescopes in arrays, they have more of a range and can offer even more accuracy. Astronomers improved radio images by connecting radio telescopes together. The discovered that two radio telescopes separated by some distance would produce a much better “image” than just one. The resolving capability of this array is equal to a radio telescope 27 km wide. Found in Sorocco, New Mexico

VLBI Very Long Baseline Interferometry It is a type of astronomical interferometry used in radio astronomy. In VLBI a signal from an astronomical radio source, such as a quasar, is collected at multiple radio telescopes on Earth. This produces images with superior resolution.

3.2 Review Questions What is electromagnetic radiation? Name four other forms of electromagnetic radiation besides visible light. How is wave frequency related to wavelength? What advantages are there to using space probes rather than manned flights? What are the sources of radio waves from space? Why aren’t television signals visible to us?