There’s a bright red star on the rise in the low eastern Everett sky in the early evening twilight. Looks can be deceiving, though, because you’re actually witnessing the rise of the planet Mars with its brilliant orange-reddish hue. There’s no mistaking Mars. As “Big Red,” it’s the brightest starlike object in that part of the sky. In fact, the only other “star” that’s brighter than Mars in the early evening sky is the planet Jupiter, still dazzling away in the southwest.
As you watch Mars climb up into the eastern sky, you can’t help but notice another bright star that’s positioned just below the red planet that actually is a star. That’s Spica, the brightest star in the large but faint constellation Virgo the Virgin. Spica is shining at us from a distance of 262 light years. That works out to be about a little under 1,540 trillion miles.
Mars, on the other celestial hand, is a heck of a lot closer, a mere 57.5 million miles from our world. That’s the closest it’s been since 2007 when it was a little under 55 million miles distant. Four years prior, in August of 2003, it was just a celestial stone’s throw away, less than 35 million miles, the closest Mars and Earth had been to each other in 60,000 years. In 2018 Mars will be almost as neighborly at just under 36 million miles from our back yards.
Every 26 months or so, as Earth and Mars travel around the sun in their respective orbits, they get into what astronomers call opposition. As you can see in my diagram the planet eventually dances into a position where the Earth lies roughly in a line between the sun and Mars. When this occurs it’s also the closest approach and minimum separation between the two planets. Opposition is also great because it puts the sun and Mars in opposite directions in our sky and that’s why they call it opposition. The benefit here is that Mars is available in the night sky all night long, rising at sunset and setting at sunrise.
Oppositions between Earth and Mars only happen every two years and two months because of the differing times it takes Earth and Mars to complete their respective orbits around the sun. It takes Earth a little over 365 days to make the circuit, but it takes Mars 687 days, so Earth laps Mars and when it does we have opposition.
The opposition distances vary greatly from cycle to cycle because of the lopsided nature of the orbits of Mars and Earth around the sun. The orbits aren’t perfect circles but are slightly oval or elliptical. Both planets have a minimum and maximum distance from the sun, called perihelion and aphelion respectively. This will greatly effect how close we get to our red neighbor in the solar system. In August of 2003, Mars was nearly at its perihelion and Earth was nearly at its aphelion. This isn’t quite the case this time around.
Even though Mars is about 23 million miles farther away and not quite as big and bright as it was in 2003, and about 22 million miles farther than it will be in 2018, you may be able to see at least some surface features on the planet, although to be honest with you it’s tricky. For one thing, Mars is much smaller than the Earth, with a diameter of slightly more than 4,000 miles, about half of Earth’s diameter.
Another viewing difficulty is that through this spring and summer Mars will never get all that high above the horizon as it arcs across the sky. In fact, the highest it will get this month will be only around 40 degrees above the southern horizon in the midnight hour. That’s less than half of the distance from the horizon to the overhead zenith. That’s a big deal because the closer Mars or any other planet is to the horizon, the more of Earth’s blurring atmosphere you will have to look through. It’s always best to wait to train your telescope on Mars or other planets until at least 90 minutes after they have risen.
Despite all that, even with a small to moderate telescope you can get a look at the surface features on Mars. Don’t go into this with wildly high expectations, however, because the valleys and mountain ranges will show up only as fuzzy dark patches on the ruddy surface. Another thing to keep in mind is that Mars rotates on its axis once every 24 hours and 39 minutes, a little slower than the Earth. This means that you’ll see more or less surface features depending on what side of Mars is facing Earth. It definitely has a plain side and a more decorative side. There’s a very good website from Sky and Telescope magazine that you can use to see what side of Mars is facing you. It’s at www.skypub.com/marsprofiler.
The easiest surface feature to see is the northern polar cap made up of frozen carbon dioxide. Keep in mind, though, that most telescopes give you an inverted upside-down view of whatever you’re gazing at. If that’s the case with your scope, Mars’ north polar cap will be situated on the lower part of the disk of Mars as your view through your scope.
The most important thing to remember about observing Mars with any size telescope is to look at the planet over extended periods of time. Brief glances don’t allow your eye to get used to the darkness and contrast in the field of view. Try to stare at Mars through your scope continually for at least 10 to 15 minutes at a time. This really works. There will be some nights when Mars will be a little fuzzy no matter how good your scope is or how much time you spend viewing it. High atmospheric winds occasionally cause too much turbulence in the air for a clear view. Try looking again on the next clear night.
Get up close with Mars this month because it won’t be this close again until 2018.
Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO radio in Minneapolis and is author of the book, “Stars, a Month by Month Tour of the Constellations” published by Adventure Publications available at bookstores at www.adventurepublications.net. If you have any astronomical questions or drop him a line at mikewlynch@comcast.net.
The Everett Astronomical Society welcomes new members and puts on public star parties. Their website is: http://www.everettastro.org/.
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