Mars is coming, and if you have a telescope, you’ll want to make the most of this opportunity in the months ahead. It’s going to be a long time before you get another good chance.
And that fact is absolutely true: Mars, the only planet whose surface we can see in detail from Earth, is now heading for the best viewing position it will offer us until 2031. Keen planetary watchers have already started to prepare their telescopes.
If you haven’t seen it yet, it’ll be worth looking for it this week, although you’ll have to wait until after midnight to see it properly.
Related: Night sky, September 2022: what you can see tonight [maps]
Mars is currently midway between the horns of the zodiacal constellation of Taurus, Taurus and during this week will rise around 10:30 p.m. local time. There is certainly no mistaking it once it appears on the east-northeast horizon. Currently shining as a brilliant pumpkin-colored light of magnitude -0.4, Mars currently ranks third after Sirius and Canopus among the 21 brightest stars. (The lower an object’s magnitude, the brighter it appears in the sky.)
But as it continues to approach our Earth in the weeks and months to come, Mars will only get brighter: it will overtake Sirius, the brightest star in the sky by November 11 and will then rank fourth among the brightest objects in the night sky. behind the moon, Venus and Jupiter.
Late Friday evening (September 16) through Saturday morning (September 17), Mars will hover about 3.5 degrees to the right and slightly below a waning gibbous moon as they rise above the east-northeast horizon (your clenched fist held at arm’s length is about 10 degrees wide). As you will see for yourself, the Red Planet will actually appear closer to a yellow-orange hue – the same color as a dry desert in bright sunshine.
It’s not often that we look closely at Mars. For starters, it’s a small world only twice the size of our moon and about half the size of our Earth. And more often than not, it spends most of the time away from us, on the other side of its orbit. I know from my many years of experience in public outreach that when I am outdoors showing the sky through my telescope, if the moon is not visible anywhere, the object that most people will ask to see is Mars.
And yet Mars ironically ranks among the most disappointing telescopic objects, usually appearing as nothing more than a tiny, featureless orange speck. The only time we get a legitimate chance of detecting the markings on its surface, polar caps, clouds and possible dust storms is about every 26 months or so when Earth approaches Mars, as our smaller and faster orbit “overtakes” Mars around the sun.
We call these oppositions, because Mars appears diametrically opposed to the sun in the sky; when the sun goes down, Mars rises. It peaks in the sky in the middle of the night and sets just as the sun begins to rise. Mars oppositions occur just over two years apart, but they are not all created equal. Because the orbits of Mars and Earth are slightly elliptical, some close approaches between the two planets are noticeably closer than others. The best come in clusters of two or three that repeat in a cycle averaging 15 to 17 years.
We are currently on the downturn of this cycle. In July 2018, Mars approached within 35.78 million miles (57.58 million km) of Earth, and in October 2020 another unusually close approach at 38.57 million miles (62. 06 million km). On this occasion, Mars will come closest to Earth on the evening of November 30 (around 9:17 p.m. Eastern Standard Time). The planet will then be 50.61 million miles (81.43 million km) from Earth, measured center to center. Mars will arrive in opposition to the sun eight days later, on December 8.
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When it makes its closest approach to Earth on November 30, the apparent diameter of Mars’ disk will be 17.2 arcseconds. To get an idea of its size, wait until after 8 p.m. this week and if you have a telescope, look at silvery-white Jupiter, shining brightly low in the eastern sky; it will appear nearly 50 arc seconds away.
In contrast, Mars’ disk will only appear about a third the size of Jupiter when the Red Planet approaches Earth later this year. While that may seem small, keep in mind that it’s still atypically large for Mars. In fact, from November 21 to December 10, the apparent size of Mars will be larger than at any time until May 2031.
The best telescope for planetary work is a high quality large refracting telescope or a large reflecting telescope with a long focal length. With almost any good telescope, however, you can still make interesting and productive observations. In any case, the limiting factor is usually atmospheric stability, which can change from hour to hour and significantly affect image quality.
For casual and serious observers, Mars offers challenges and, hopefully, delights. In a high quality 4 or 6 inch (10 or 15 centimeter) telescope on a night of excellent, stable air, you may be able to see the North Polar Cap, dark surface features, clouds, and events. of dust. Using a magnifying eyepiece at 105 power will cause the disc of Mars to appear the same angular size as the moon to the naked eye.
A marking may only appear fleetingly the first time you see it. But over the next few nights, as you become familiar with its appearance, you’ll be able to recognize it right away — and perhaps see details that were invisible to you at first. Just remember:
The more you look, the more you will see.
Size isn’t everything
As we noted at the start, Mars is already shining brightly in our night sky, beckoning observers to see what they can see. On November 7, you’ll catch the planet high in the east-southeast sky at midnight. After his Dec. 8 opposition, it will be an early evening item in the months to come as he moves away.
So almost as if to compensate for its relatively small apparent size, Mars will literally hover in the night sky. In fact, this year’s observing season shows Mars straddling near the northernmost part of the ecliptic, in Taurus above Orion. This means it passes very high overhead each night for observers at mid-northern latitudes – well above the thick layers of air and poor atmospheric visibility that troubled northern observers during its exceptionally close passage to Earth during the summer of 2018.
December 7: M&M Night
Finally… be sure to put a big circle on your calendar on Wednesday, December 7th. During the evening hours, the full moon will pass extremely close over Mars, in effect hiding it (called an occultation) for parts of North America, and no doubt raising a question that will be repeated many times. that night: “What is that bright yellow-orange star just below the moon?” On this night, even the most laid-back people will turn their attention to Mars.
Good observation of Mars!
Joe Rao is an instructor and guest speaker at New York’s Hayden Planetarium (opens in a new tab). He writes on astronomy for natural history review (opens in a new tab)the Farmers Almanac (opens in a new tab) and other publications. Follow us on twitter @Spacedotcom (opens in a new tab) and on Facebook (opens in a new tab)
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