Elusive Mercury Visible at Dawn This Week

Even though the planet Mercury is one of the brightestobjects in the sky, it is one of the most rarely seen. But this week is one ofthe few occasions when the small planet is well-placed for skywatchers.

Although Mercuryis always brighter than Saturn at its brightest, very few stargazers have everseen it. As the innermost planet in the solar system, it never strays far fromthe sun, so is always seen against a bright background of twilight.

Twice each year, once in the evening and once in themorning, Mercury stands highest in the sky, giving skywatchers the best opportunityto spot it, weather permitting. This week is its best morning appearance of thewhole year.

This sky map shows where to look to see Mercury.

Rise and shine Mercury

To try and see Mercury, skywatchers should go out anymorning this week about a half hour before sunrise. You will need a lowcloudless sky and unobstructed view of the eastern horizon.

Look just above where the sun will rise and you shouldspot tiny Mercury about 10 degrees above the horizon. A human fistheld at arm's length covers about 10 degrees of the sky.

You may have to sweep with binoculars to see Mercury atfirst, but once spotted it should be visible to the unaided eye.

In a smalltelescope, you will see Mercury as a tiny half moon. It will probably look asif it?s submersed in boiling water because of the turbulence of the Earth?satmosphere.

If you track Mercury with your telescope as it rises inthe sky, the view should become steadier. Mercury will continue to be visiblein your telescope after the sun rises, as it is bright enough to be visiblethrough the blue sky, so long as you know exactly where it is.

Mercury: A strange planet

Mercury is one of the strangest worlds in the solarsystem. [10Mysteries of Mercury]

It is the smallest planet, now that Pluto has beenreclassified as a dwarf planet, at 3,032 miles (4,879 km) in diameter, onlyslightly larger than our moon. It has an odd, slow rotation period, 58.6 days,exactly two-thirds the time it takes to complete an orbit around the sun.

The surfaceof Mercury, as imaged by the two space probes that have visited it, looksvery much like that of our moon, though with more craters and fewer openplains. It also experiences the greatest temperature extremes of any planet,ranging from 800 degrees Fahrenheit (426 degrees Celsius) to minus 280 degreesF (minus 173 degrees C) between day and night.

Legend has it that Johannes Kepler, who discovered thelaws of planetary motion, never saw Mercury with his own eyes. This week isyour chance to see the planet that Kepler missed?worth getting up early to see.

This article wasprovided to SPACE.com by StarryNight Education, the leader in space science curriculum solutions.

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Geoff Gaherty
Starry Night Sky Columnist

Geoff Gaherty was Space.com's Night Sky columnist and in partnership with Starry Night software and a dedicated amateur astronomer who sought to share the wonders of the night sky with the world. Based in Canada, Geoff studied mathematics and physics at McGill University and earned a Ph.D. in anthropology from the University of Toronto, all while pursuing a passion for the night sky and serving as an astronomy communicator. He credited a partial solar eclipse observed in 1946 (at age 5) and his 1957 sighting of the Comet Arend-Roland as a teenager for sparking his interest in amateur astronomy. In 2008, Geoff won the Chant Medal from the Royal Astronomical Society of Canada, an award given to a Canadian amateur astronomer in recognition of their lifetime achievements. Sadly, Geoff passed away July 7, 2016 due to complications from a kidney transplant, but his legacy continues at Starry Night.