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Astronomy: Get the Message about Mercury

Mercury by MESSENGER Mercury as seen by MESSENGER. Image Credit: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington

The first spacecraft ever to orbit Mercury reached the fleet-footed planet in March of this year. MESSENGER, which stands for Mercury Surface, Space Environment, Geochemistry, and Ranging, is revealing a world not seen before. Among other tasks performed by MESSENGER, it is mapping the planet’s landforms and sampling its magnetic field. One of the interesting discoveries already made is the existence of unusual pits in the bottom of crater floors that may have been created by volatile materials in the planet’s crust.

A spacecraft visiting Mercury was necessary to get a good view of the planet, because Mercury is positioned too close to the sun for the Hubble Space Telescope to ever try to capture an image of it.

You can get a look at Mercury yourself starting now and continuing over the month of July. Mercury is currently in the west-northwest after sunset, shining at magnitude -0.9. Mercury is in the constellation Gemini, below the stars Pollux and Castor, but it will slip upwards until it is in nearly a straight line with the two stars on June 29 and 30.

Over the coming weeks, Mercury will fade as it diminishes from its 85-percent-lit face to only 23-percent-lit on July 31. Mercury won’t stay in Gemini long. It climbs into Cancer by July and enters the Beehive Cluster on the 6th. It swings by Regulus in Leo at the end of July and will then shine at magnitude 0.9, which, although dimmer, is still brighter than Regulus.

While Mercury is visible without any optical aid, using binoculars or a telescope will help you to see the phases that the planet undergoes as it shrinks from a gibbous to a crescent.

-- Kelly Kizer Whitt loves clean, clear, and dark skies. Kelly studied English and Astronomy at the University of Wisconsin-Madison and worked for Astronomy magazine. She writes the SkyGuide for AstronomyToday.com. You can follow her on Twitter at twitter.com/Astronomommy.

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