Take a tour of the Whirlpool galaxy, with views from early astronomers and NASA space telescopes.
Transcript:What's Up for April? Did you know you can see other galaxies through modest telescopes or binoculars? Well you can!
Hello and welcome. I'm Jane Houston Jones at NASA's Jet Propulsion Laboratory in Pasadena, California
During 2009, we're celebrating International Year of Astronomy by taking you on a tour of one of the month's best celestial objects. This month, it's the Whirlpool Galaxy!
Join me as we step away from our solar system, look beyond our own galaxy, and view the spiral arms of another galaxy.
Because we are inside our own galaxy - about two-thirds of the way from the galactic core, we can't see the whole thing. But we can see the spiral arms and so we know we live in a spiral-shaped galaxy.
Early astronomers looked up in the night sky and saw patches of light which appeared like faraway clouds. They called these patches nebulae.
In 1845, Ireland's Third Earl of Ross, William Parsons, used his huge telescope at Birr Castle in the center of Ireland to observe and sketch the spiral structure of the Whirlpool Galaxy.
Other 18th and 19th century astronomers, including father and son William and John Herschel, noted the structure of this galaxy, too.
A galaxy is an enormous collection of gas and stars held together by gravity. Since the 19th century, astronomers have aimed telescopes at galaxies, discovering their composition.
In the 20th century, NASA'S orbiting telescopes have looked at this amazing galaxy to see it in many portions of the electromagnetic spectrum, from radio to infrared, on to visible light, and past visible to ultraviolet, X-Ray and on to gamma ray.
NASA's Spitzer Space Telescope looks at galaxies in the infrared part of the spectrum. It can see long lanes in the spiral arms. They are stars and gas laced with dust.
The Hubble Space Telescope sees similar views in a different wavelength. It looks at the optical part of the spectrum or what we think of as visible light. That's the light we can see.
NASA'S Chandra X-ray observatory reveals black holes, neutron stars and a glow between the stars of the Whirlpool Galaxy.
And last, but not least, the GALEX telescope shows that hot young stars produce a lot of ultraviolet energy.
Don't forget to view Saturn this month either. It's higher in the sky and easier to see.
You can read all about the Whirlpool and other galaxies in the distant universe this month on NASA's International Year of Astronomy website: astronomy2009.nasa.gov
And you can learn all about NASA's missions at: www.nasa.gov
That's all for this month. I'm Jane Houston Jones.
Thanks to the following for submitting images:
Birr Castle Archives
NASA, Jet Propulsion Laboratory, California Institute of Technology