What Will Your Telescope Show On Mars?

Mars is currently in retrograde motion moving to the west, but it turnabout in early July and resume its normal eastward motion, speeding from Scorpius and Sagittarius (the Teapot). Created with Chris Marriott's SkyMap
Mars is currently in retrograde motion moving to the west but will make an about face in early July and resume its normal eastward motion, speeding from Scorpius across Ophiuchus and into Sagittarius (the Teapot). Saturn’s position is shown for late May. Created with Chris Marriott’s SkyMap

Yesterday, we explored Mars with the naked eye. Today, we’ll point a telescope at it. For observers in the northern hemisphere, Mars remains low in the sky throughout its current apparition, never climbing more than a few fists above the southern horizon. Because we view the planet through the bottom of the atmosphere where air turbulence is greatest, images are rarely as sharp in the telescope as we’d like.

To the naked eye, Mars may appear bright and serene, but when magnified, it oozes and flutters about, challenging the observer to catch what details he or she may. That’s part of the fun and challenge of observing planets! But there are things we can do to maximize the opportunity to see Martian surface features. The first is to observe the planet every clear night you can around opposition, when it’s closest to Earth.

Expert astroimager Damian Peach created this photographic map of Mars labeled with its most prominent features visible in amateur telescopes. Click for a large version. Credit: Damian Peach
Expert astroimager Damian Peach created this photographic map of Mars labeled with its most prominent features visible in amateur telescopes. Click for a large version. Credit: Damian Peach

The more often you look, the more likely you’ll hit that ideal night when the air settles and Mars pops into sharp view. This may sound strange, but without turbulence, the planet looks far more REAL. Like you’re orbiting it in a spaceship. As you get further acquainted, you’ll also be training your eye to know precisely what to look for. No time time spent at the telescope is ever wasted.

The easiest dark marking to see on Mars in a small telescope is the finger-shaped Syrtis Major seen here in the center of the disk. At top, clouds and frost cover the planet's largest crater, Hellas. Credit: Christopher Go
The easiest dark marking to see on Mars in a small scope is the Syrtis Major seen here in the center of the disk. At top, clouds and frost cover the planet’s largest crater, Hellas. Credit: Christopher Go

Second, if you observe the planet when it’s higher up instead of close to the horizon, it will always appear sharper. For a clear view, wait till Mars is at least 15° or one and half fists high above the horizon. In late May, that means around 11 o’clock or later. By mid-June, you can start at 1o.

Third, use a red filter on your eyepiece. Red increases the contrast between the pale dark markings and their bright surroundings. It also helps to “calm” atmospheric turbulence a bit.

This panel shows nearly a full turn of Mars. On some nights, the "blank" hemisphere will be turned your way and you'll see little but the thin strip of M. Sirenum; other nights, the planet is rich with detail especially if the air turbulence is low. Credit: Christopher Go with labels by the author
This panel of photos, all taken between April 30 and May 16, 2016, shows almost a full rotation of Mars. On some nights, the “blank” hemisphere will be turned your way and you’ll see little but the thin strip of M. Sirenum; other nights, the planet presents a hemisphere rich with detail. South is up. Click for a large view. Credit: Christopher Go with labels by the author

Even a small 3 or 4-inch telescope magnifying around 60x will show the planet’s colorful orange disk that clearly distinguishes it from the point-like stars. Cranking up the power to around 150x will bring out the largest dark features, the easiest of which to see is Syrtis Major, an ancient and now extinct shield volcano shaped like a pointing finger. Small scopes will also reveal several other dark “seas” or maria such as Erythraeum, Tyrrhenum, Cimmerium and Acidalium as well as mists and clouds that whiten the planet’s limb.

Mars’ surface markings names come from ancient Greek mythology and sound like poetry when you say them out loud, which I encourage you to do.

I've marked the most obvious features on this map of Mars which shows the hemisphere turned toward the Americas this weekend at 11 p.m. CDT. If you observe Mars later - around midnight or into the early morning hours - , say around
I’ve marked the most prominent features on this map of Mars which shows the hemisphere turned toward the Americas this weekend around 11 p.m. CDT. If you observe Mars later, say around midnight or from a time zone further west, features in the east (right side in the south-up view) will have rotated closer to the center of the planet, while those in the west will pass out of view. Diagram: Bob King, source: Claude Duplessis Meridian software

Telescopes from 6-inches up will reveal much more to the patient eye. Through my 10-inch at 200x, Syrtis Major and the large seas are obvious, but more subtle features such as the current cloud cover over the Hellas impact basin (Mars’ largest crater), the gap between Mare Acidalium and Niliacus Lacus to its south and the chicken leg-shaped duo of Sinus Sabaeus and Sinus Meridiani are readily seen. If we’re lucky, Mars might even cook up a dust storm for us this season. Keep an eye out for a small yellowish patch of light that marks the onset of a storm.

I wish one or both of the Martian polar caps were visible, but currently see Mars pretty much straight up and down rather than with one or the other pole tilted our direction. Both caps are hidden in hazes or clouds along the planet’s edge or limb.

Mars around 11 p.m. one week from now on May 28 shows a fairly blank hemisphere with M. Sirenum/M. Cimmerium appearing as a narrow band across the planet's southern hemisphere. Many more features will return to view the following week, when I'll do an update. Created with Meridian by Claude Duplessis
Mars around 11 p.m. one week from now on May 28 shows a fairly blank hemisphere with M. Sirenum/M. Cimmerium appearing as a narrow band across the planet’s southern hemisphere. The huge, bright plain called Amazonis Planitia occupies the center. Many more features will return to view the following week, when I’ll do an update. Diagram: Bob King, source: Claude Duplessis Meridian software

Not to fret. This week and early next, part of Mars’ feature-rich hemisphere will face observers in the Americas. I’ve included a couple maps to help you identify major dark markings as well as a large photographic map you can download onto your own device to consult as needed. As a further guide, you can always find out which part of Mars is visible when by checking heading over to Sky & Telescope’s Mars Profiler. If you miss seeing the markings you’d like to view because of weather, poor seeing or commitments, Mars’s rotation will bring them back around in a few weeks.

To summarize:

* Observe every clear night during the next few weeks to both train your eye and catch a night of “steady air.”

* Use as much magnification as possible — to a point. I rarely go above 250x; anything beyond that and the atmosphere blurs the image too much. But if the air allows, go as high as you can go! Try a red filter, too.

* Anticipate and inform your Mars observing by checking to see what hemisphere of Mars is facing you and keeping a map handy to look for markings visible on that hemisphere. Mars rotates once every 24 hours and 37 minutes — just a bit longer than one Earth day — causing features to gradually drift to the east night after night with new features coming into view along the planet’s west side.

If you observe the Red Planet often, you might start to feel that you’re living on Mars time rather than Earth’s clock! A first step to becoming a Martian.

2 Responses

  1. Marshall R. Angeles

    Hi Bob,
    Just a FYI – Dr. August Dunning’s Mars weather report at 3:13. Very nice videos of surface at end.
    Regards,
    Marshall

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