Cruithne: Earth's Other 'Moon' Could Reveal Mysteries Of The Solar System
Cruithne: Earth's Other 'Moon' Could Reveal Mysteries Of The Solar System
By The Conversation | February 26th 2015 01:30 PM
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Artist's illustration of the Aragoscope, a space telescope concept that would use a light-diffracting
disc to produce ultrasharp images.
Credit: NASA
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3753 Cruithne's wacky orbit around the Sun. Image: YouTube, CC BY-SA
We all know and love the moon. We’re so assured that we only have one that we don’t even give it a specific name.
It is the brightest object in the night sky, and amateur astronomers take great delight in mapping its craters and seas.
To-date, it is the only other heavenly body with human footprints.
What you might not know is that the moon is not the Earth’s only natural satellite. As recently as 1997, we discovered that another body, 3753 Cruithne, is what’s called a quasi-orbital satellite of Earth. This simply means that Cruithne doesn’t loop around the Earth in a nice ellipse in the same way as the moon, or indeed the artificial satellites we loft into orbit. Instead, Cruithne scuttles around the inner solar system in what’s called a “horseshoe” orbit.
To help understand why it’s called a horseshoe orbit, let’s imagine we’re looking down at the solar system, rotating at the same rate as the Earth goes round the sun. From our viewpoint, the Earth looks stationary. A body on a simple horseshoe orbit around the Earth moves toward it, then turns round and moves away.
More:
http://www.science20.com/the_conversation/cruithne_earths_other_moon_could_reveal_mysteries_of_the_solar_system-153513
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