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Mars

The Backyard Astronomer by Adam England


On October 6 the planet Mars made its closest approach to Earth, putting it only 38.6 million miles away.


We call this close approach 'opposition,' meaning when the Earth and Mars are in a direct line on the same side of the Sun. Because orbits are not perfectly circular, sometimes we are a little farther away, sometimes a little closer at opposition. Since that point we've been get a little farther apart every day. But don’t worry, you will still have great views of Mars through the fall.


Mars as drawn by Percival Lowell near the turn of the 20th century.

From the earliest times our ancestors knew Mars was special. Colloquially identified with the Roman god of war, Mars appears as a bright red dot in the sky, in stark contrast to the many white and blue stars around it. Although this name derives from its color, associated with the blood of war, we now know the soil is rich in iron and what we see is essentially the oxidized or rusty surface soil. Many other cultures have named the planet with words meaning 'fire' or 'red.'


Mars is also a wanderer, moving from night to night and traversing the sky with the seasons. At opposition it is the third-brightest object in the sky after the moon and Venus. At its most distant from Earth it is directly opposite us on the other side of the sun and not visible. Because the sun’s extreme radiation hinders direct communication during these times, NASA relies on other orbiting satellites to relay messages from our rovers on the planet.


Galileo turned his rudimentary telescope to Mars in 1610, starting an ever-increasing rush observations of the planet. With each improved generation of telescope we learned more about our cosmic neighbor. Within a century after Galileo we could distinguish its polar ice caps from the surrounding regolith, and by the late 19th century maps of the Martian “canals” were common, giving rise to stories of alien cultures and planet-wide engineering projects.


Modern exploration has helped us understand that at one time Mars probably had liquid water that could have sustained life. Now the atmosphere is much too thin, at just 1% of sea-level pressure on Earth, and the ice caps hold massive amounts of carbon dioxide, with some extremely salty deposits of water ice.


PAC member Joel Cohen shot this view of Mars from Prescott Valley, Oct. 2.

To catch a glimpse of the Red Planet in November, look to the eastern horizon after dark and trace upward till you find the bright red dot. With even the most basic backyard telescope or binoculars you will begin to see the ice caps and surface features of one of our closest planetary neighbors. Catch the show now, though, it won't come again till 2034.


To learn more about the sky, telescopes, or socialize with other amateur astronomers, visit us at prescottastronomyclub. org or Facebook @PrescottAstronomyClub to find the next star party, Star Talk or event.


Adam England is a local insurance broker who moonlights as an amateur astronomer, writer, and interplanetary conquest consultant. Follow his rants and exploits on Twitter @AZSalesman or Facebook.com/insuredbyadam

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