Discovery of Uranus' Rings

We have discussed before that all the gas planets in the solar system have rings.  Even through a small telescope Saturn has visible rings, but Jupiter, Uranus and Neptune do not. So how did astronomers discover their rings in the first place?

Hubble image of Uranus and its rings

The rings around Uranus were discovered in 1977. Astronomers knew that Uranus was going pass in front of a distant star in the night sky, from Earth's perspective. They pointed their telescopes to towards the planet each night, and expected to see the planet block the light from the star only when the star was directly behind the planet. What they actually observed was the star flickering right before and right after is passed behind the planet. This meant that there must be some unseen object near the planet blocking the starlight! The only plausible explanation was that Uranus has very thin, dim rings that are not visible from telescopes here on Earth. In 1986, Voyager flew by Uranus and imaged the rings for the first time, proving  their existence. Since then, we have discovered rings around Jupiter and Neptune in similar ways.

NASA Missions Extended

 

Artists conception of Spitzer, Planck and Kepler (left to right)

Astronomers received some great news a few days ago. Three major space telescopes, Kepler, Spitzer and Planck, have had their missions extended! This is great news, as astronomers will obtain more data and hopefully make some big discoveries! But what can we do with these telescopes?

The Kepler Space Telescope is an optical telescope has been actively searching for exoplanets. It looks at the same region of the sky 24/7, and measures the brightness of 150,000+ stars. If one of them dims for a short period of time, it might be due to a planet crossing in front of the star and blocking the light. Kepler has already found over 2000 potential exoplanets in the last 2.5 years of operation, and it's funding has been extended until 2016

The Spitzer Space Telescope is an infrared telescope that has been operating since 2004. For the telescope's detector to work properly, it needs to be kept extremely cold. Unfortunately, the cryogenics which keep it cool have run out, but the detector still functions, and some science can be done with the telescope. Astronomers have used Spitzer to look at young stars, distant galaxies, and many other objects that are "hidden" behind giant clouds of gas.  It will continue to operate for another two years.

Planck is a jointly funded NASA and ESA telescope which has been operational for about three years. It's a space based microwave/radio telescope whose main purpose is the study the cosmic microwave background. This is the first light emitted by the universe after the Big Bang. It will help us understand how the universe began by observing it right after it was born. Astronomers also use Planck to study distant galaxies, and objects in our solar system.

Image Credit:  NASA/JPL-Caltech