Weekly astronomy column: Mars is on a rendezvous with the Earth. On Jan. 27, they were closest as the two planets came into conjunction in their orbital paths about the sun.
Mars is on a rendezvous with the Earth. On Jan. 27, they were closest as the two planets came into conjunction in their orbital paths about the sun.
Some people are known to fret over these things. Despite some ridiculous e-mails that make the rounds of cyber-space, Mars never approaches so close that you an see its round disc with the naked eyes, or its gravitational field causes earthquakes. It simply doesn’t happen. Heaven knows, the Earth quakes enough on its own without any neighboring planet helping out.
This is a rather mediocre close approach; the planets have elliptical orbits rather than perfect circles, so their passage approximately every two years varies a great deal. At this conjunction, Mars is approximately 61,720,800 miles away. Mars does reaches aphelion (its point farthest from the sun) on March 31.
The perihelion point of Earth (when we are closest to the sun) occurred Jan. 3. On that day we were 91.405 million miles from our star; it won’t reach aphelion until July 4, when Earth will be at its maximum distance, 94.512 million miles.
Mars varies from 128.6 million to 160 million miles from the sun. Obviously, the orbit of Mars is much more elliptical than Earth’s.
The closest possible approach between the two planets is when Earth is at aphelion and Mars is at perihelion, at the same time. This brings us only 34.088 million miles apart. This time Mars is 61.7 million miles away.
How far is that? Consider, the Earth is 7,926 miles wide at the equator. It would take 7,787 earths end to end to reach the distance of Mars.
Still, the Red Planet is impressive in the eastern evening sky. It is shining at magnitude –1.3, just a little but less luminous than Sirius (magnitude –1.45), the brightest star in the night sky. Blue-white Sirius may be seen far to the right of Mars, the southeast.
With the Martian year nearly twice that of the Earth year, Mars comes near only once in about 26 months. On “off” years, Mars appears considerably dimmer, about magnitude +2 (similar to the stars of Orion’s Belt or the brighter stars of the Big Dipper). Its brightness at close approach, however, varies in a cycle of 15 to 17 years.
It’s interesting to ponder that while you gaze up at Mars, several robots from Earth are dutifully studying the planet, both on the dusty ground and from Martian orbit.
This is the closest Mars will be until 2012. If you have a telescope, see what you it will show you. You should be able to tell at once that Mars is more than a star-like point of light. Using a low power eyepiece, look for its tiny, pale orange disc. Magnification of 100x or more might show you a bit more, but don’t be surprised if it looks like a quivering, orange blob. Unsteadiness in our atmosphere makes the planet’s image shiver and shake. So does any vibration to your telescope.
If you have an open-ended reflector telescope, you should set it outside in the cold air for an hour or even more before using it with high magnification. Warm air from inside the house needs to flow from the telescope tube. Otherwise, your high powered views of Mars, the moon or anything else, will be affected by the turbulant air drifting out.
On rare nightsof good “seeing” - when the air is still, you may be able to see the white North Polar Cap on Mars, and vague, gray smudges on the planet surface. I was looking the other night, and marveled at how easy it was to see the bright white cap. For interest, I glanced at the snow on the ground, lit by the Moon, and then looked back at the Martian polar snow and ice, as seen in the eyepiece. Either way, it was snow!
Full moon occurs Jan. 30, and last-quarter moon is on Feb. 5.
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Keep looking up!