Seeing into Space!

The Earth at Night as computer generated by multiple images. http://antwrp.gsfc.nasa.gov/apod/ap001127.html

The Earth At Night Where would be the best location for large telescopes? Somewhere where there is little light pollution…. The glow of lights from cities reflects off the earth’s atmosphere, making it difficult for observers of the night sky to see anything but the brightest stars.

Mauna Kea, Hawaii located at the highest points possible to reduce the effects of atmosphere refraction dry air regions to reduce the effect of star twinkling – caused by star light being randomly refracted (bent) by moisture in the atmosphere areas with no cloud cover and storms (especially dust) close to the equator so that most of the sky can be seen. South African Astronomical Observatory, since 1972

Types of Telescopes Reflecting – use mirrors to bend the light and cause magnification (best for larger images). Refracting – uses lenses to bend the light (best for clearer images). Combination – a lens at the front and an objective mirror at the back. Resolving Power is determined by the width of the objective lens or objective mirror. It is the fineness of detail. Magnification = Focal length of objective lens Focal length of ocular lens (Focal length is the distance from the lens to the image of the object that is far away)

Reflecting Telescope The largest optical telescopes are reflecting rather than refracting telescopes because it is easier to build and support large mirrors rather than lenses.

Ritchley 24” Reflecting Telescope The largest single mirrors are about 8 m across.

Refracting Telescope Chabot Space and Science Center in Oakland, California. The objective lens is 21 cm in diameter.

How a Refracting Telescope Works

Bigger and Better The bigger the telescope, the deeper into space we can see. Using computers, images from two different telescopes can be combined. This makes the distance between the two telescopes equal to the resolving power. The largest pair is Keck I and Keck II in Hawaii. (Why Hawaii?)

http://antwrp.gsfc.nasa.gov/apod/ap971227.html In buildings eight stories tall, rest mirrors ten meters across that are slowly allowing humanity to map the universe. Alone, each is the world's largest optical telescope: Keck. Together, the twin Keck telescopes have the resolving power of a single telescope 90-meters (a football field!) in diameter, able to discern light sources just milliarcseconds apart. Since opening in 1992, the real power of Keck I (left) has been in its enormous light-gathering ability - allowing astronomers to study faint and distant objects in our Galaxy and the universe. Keck II, completed in 1996, are located on the dormant volcano Mauna Kea, Hawaii, USA.

Images from Keck Io’s Volcanic Surface (A moon of Jupiter) http://alamoana.keck.hawaii.edu/news/archive/io/io_close_lowres4M.mpg

The center of our Milky Way galaxy, as seen in the infrared using the Keck Laser Guide Star. The white cross marks the location of the supermassive black hole 26, 000 light years away. http://www.keckobservatory.org/news/science/051220_bhole/051220b.html Black holes are collapsed stars so dense that nothing can escape their gravitational pull, not even light. Black holes cannot be seen directly, but their influence on nearby stars is visible, and provides a signature. The supermassive black hole, with a mass more than three million times that of our sun, is in the constellation of Sagittarius. The galactic center is located due south in the summer sky. The black hole came into existence billions of years ago, perhaps as very massive stars collapsed at the end of their life cycles.

So What is a Light Year? There are two units of measure large enough to measure distances in space: AU – Astronomical Unit The distance from Earth to the Sun 150 million km Useful only within our solar system Light-year The distance light travels in one year About 63 240 AU About 9 486 billion km!

Exoplanets – Outside our Solar System! The red object is the planet, and the white object is the brown dwarf star around which it travels. Both objects are believed to be very young, less than 10 million years old. Space - the final frontier!!

The Hubble – We’ve come a long way since Galileo’s first telescope Facts: Named after Edwin Hubble, who confirmed an expanding universe and set the ground work for the big bang theory This space telescope orbits the earth in what is called a low earth orbit. That means it travels around the earth like the moon, but it is lower down. It does not require power to move. It does however require power to operate. How do we get power up there?

We don’t! It’s equipped with solar panels that harvest energy from the sun’s radiation What’s the point of having a space telescope?

Remember that pesky earth’s atmosphere that makes the stars twinkle? That same pesky earth’s atmosphere interferes with images from space that earth telescopes pick up – called distortion. The Hubble’s position ensures that none of that pesky atmosphere interferes with images that the Hubble picks up

The result is awesome pictures And an explosive amount of knowledge about the universe!

What kind of telescope is Hubble? Tell me! HubbleSite - The Telescope - Nuts & Bolts - Optics Where is Hubble now? What has Hubble shown us? More about Hubble and its absolutely ground breaking discoveries can be found at www.hubblesite.org

What is a light year? Reflecting telescopes use _________ to view objects Refracting telescopes use _________ to view objects What is resolving power of a telescope? What effect does diameter of mirrors and lenses have on resolving power? What is focal length? What effect does focal length have on magnification? What’s the advantage to having a telescope like the Hubble outside of earth’s atmosphere? How does the Hubble telescope get power? What kind of telescope is the Hubble?