Mars is coming, and if you have a telescope, you’ll want to make the most of this opportunity in the coming months. It will be a long time before you get another good chance.
And this fact is absolutely true: Marsthe only planet whose surface we can see in any detail from a landis now moving towards the best viewing location it will provide us until 2031. Diligent planetary observers are already beginning to equip their telescopes.
If you haven’t seen it yet, it will be worth looking for it this week, although you’ll have to wait until midnight to see it well.
Mars is currently located halfway between the two horns of the zodiac the Bull, Taurus and during this week it will rise at about 10:30 pm DSST. There is certainly no doubt that once it appears above the eastern and northeastern horizon. Mars currently shines like a bright pumpkin light with a magnitude of -0.4, and is currently ranked third after Sirius and Canopus among the 21 brightest stars. (The lower the size of the object, the brighter it is in the sky.)
But as it continues to get closer to Earth in the coming weeks and months, Mars will only get brighter: it will overtake it. Siriusthe brightest star in the sky by November 11, then will occupy the fourth position in the night sky behind Moon, Venus and Jupiter.
Late Friday night (September 16) and into early morning Saturday (September 17), Mars will hover about 3.5 degrees to the right and just below the waning moon as it rises above the east-northeast horizon (your clenched fist that Held at arm’s length about 10 degrees in width). As you will see for yourself, the red planet will actually appear closer to the yellow-orange color – the same color as the dry desert under the high sun.
It’s not often that we take a close look at Mars. First of all, it is a small world, twice the size of the moon and about half the size of the planet Earth. And more often than not, it spends most of the time far away on the other side of its orbit from us. I know from my many years of public outreach experience, that when I view the sky outside through my telescope, if the Moon is nowhere to be seen, the thing most people will ask to see is Mars.
However, paradoxically, Mars is classified as one of the Most disappointing Telescopic objects, usually appearing as nothing more than a small, featureless orange dot. The only time we get a legitimate shot of spotting signs on its surface, polar caps, clouds, and potential dust storms roughly every 26 months or so, is when Earth approaches Mars, as our smaller, faster orbit “overtakes Mars around the Sun.”
We call these contrasts, because Mars appears exactly opposite to the Sun in the sky; When the sun sets, Mars rises. It reaches its highest point in the sky at midnight and sets just as the sun begins to set. Opposition to Mars occurs a little over two years later, but not all are created equal. Since both the orbits of Mars and Earth are moderately elliptical, some close approaches between the two planets are noticeably closer than the other. The best comes in groups of two or three repeated in a cycle averaging 15 to 17 years.
We are now in a downturn in that cycle. In July 2018, Mars reached an extraordinary distance of 35.78 million miles (57.58 million km) from Earth, and in October 2020 another unusually close approach came at 38.57 million miles (62.06 million km). On this upcoming occasion, Mars will approach Earth on the evening of November 30 (around 9:17 p.m. EDT). The planet will then lie 50.61 million miles (81.43 million km) from Earth as measured from one center to the other. Mars will reach the sun eight days later on December 8.
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When it approaches Earth on November 30, the diameter of the apparent disk of Mars will be 17.2 arc seconds. To get an idea of just how large this size is, wait until 8 p.m. this week and if you have a telescope, check out the silvery-white, shiny Jupiter low glisteningly in the eastern sky; Approximately 50 arc seconds will appear across.
In contrast, the disk of Mars will appear about a third the size of that of Jupiter when the red planet approaches Earth later this year. While this may sound small, keep in mind that this is still unusually large for Mars. In fact, from November 21 to December 10, the apparent size of Mars will be greater than at any time until May 2031.
The best telescope for planetary work is a large, high-quality refracting telescope or a long-focus reflecting telescope. With almost any good telescope, you can still make interesting and fruitful observations. In any case, the limiting factor is usually atmospheric stability, which can vary from hour to hour and greatly affect image quality.
For both casual and serious observers, Mars presents challenges and – with a little luck – delights. In a high-quality 4 or 6 inch (10 or 15 cm) telescope on a night of excellent still air, you might be able to peek into the arctic cap, dark surface features, clouds, and dust. Using a magnifying glass with a power of 105 makes the disk of Mars appear the same angular size as the moon appears to the naked eye.
The sign may only appear in passing the first time you glimpse it. But over the following nights, as you become aware of her appearance, you’ll be able to instantly recognize her—and perhaps even see details that were initially invisible to you. Just remember:
The more you look, the more you see.
Size is not everything
As we noted at the beginning, Mars is already shining in the late night sky, inviting observers to see what they can see. By November 7, you’ll catch the planet high in the east-southeast sky by midnight. After opposing December 8, it will be an early evening object over the following months as it recedes into the distance.
So almost as if to make up for its relatively small apparent size, Mars would literally rise up into the night sky. In fact, this year’s observing season finds that Mars rides near the northernmost part of the ecliptic, in Taurus above. Orion. This means that it passes very high every night for observers in the mid-northern latitudes – well above the thick layers of air and poor atmospheric visibility that bothered northern observers during its exceptionally close pass 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 7. During the evening hours, the full moon will pass so close to the surface of Mars, actually obscuring it (called the unseen) for parts of North America, and no doubt will raise a question that will be repeated many times that night: “What is this bright yellow?—an orange star just below the moon ?” That night, even the most casual will turn their attention to Mars.
Happy Mars watch!
Joe Rao works as a teacher and guest lecturer in New York Hayden Planetarium (Opens in a new tab). He writes about astronomy for Journal of Natural History (Opens in a new tab)The Farmers’ calendar (Opens in a new tab) and other publications. Follow us on Twitter Tweet embed (Opens in a new tab) and on Facebook (Opens in a new tab)