Go look at Mars!

By Phil Plait | March 26, 2012 11:00 am

These past few days the Moon, Venus, and Jupiter have been showboating in the west right after sunset. They’re so bright they’re mesmerizing, but you’re missing something if you literally don’t turn around. Sitting in the belly of Leo the Lion is the next planet out from the Sun: Mars.

[Click to enaresenate, and also see a way cool animation of Mars rotating.]

That’s the view seen by frequent BABlog contributor Emil Kraaikamp, who takes pretty amazing astrophotos. But even by eye, Mars is dazzling.

It orbits the Sun farther out than Earth does, so we overtake it every couple of years or so. When that happens Mars and Earth are as close together as they can be — think of it like two cars on a racetrack, so when one passes the other they’re in close proximity, and every other time a lot of distance separates them. This just happened a few weeks ago, so Mars looks amazing right now.

In fact, because Mars is close, it’s been the target of many amateur astronomers recently. Wayne Jaeschke was observing it on March 20th from West Chester, Pennsylvania and noticed something odd: a blob or bulge on the edge of the planet!

[Click to see the original; I brightened the image to make the anomaly more obvious. Go to the CloudyNights forum to see lots more pictures and discussion!]

This is almost certainly a high-altitude cloud of some sort; Mars does have an atmosphere and weather. Clouds over the Red Planet are common enough, and can be spotted through small telescopes, though one at this altitude is unusual. They’ve been seen before like this, so it’s not completely unheard of, but that doesn’t make it any less interesting! Wayne also put up an amazing animation where you can see the cloud on the upper right edge of the planet, and you really get a sense of how high up it is. Alan Boyle at Cosmic Log has more.

But you don’t need a telescope to go out and look! I was out the other night, in fact, and saw the bright star Arcturus rising in the east. Mars and Arcturus are both about the same brightness right now, and also both very close to the same color — Arcturus is a bright orange giant star, much like the Sun will be in a few billion years. If you live in the northern hemisphere, go out around 11:00 p.m. and face northeast. You’ll see the Big Dipper easily enough; extend the arc of the handle down and to the right and you’ll see Arcturus like a charcoal ember glowing in the sky (as we astronomers like to tell people, "Follow the arc to Arcturus").

But if you do have a telescope, now’s the time to look. As our planet pulls away from Mars, it’ll look ever smaller through the eyepiece. Not that Mars is all that big; it’s 1/3 the Earth’s diameter and still 100 million km away! But you never know what you might see.

Image credits: Emil Kraaikamp; Wayne Jaeschke; both used with permission.

Related Posts:

The blue clouds of the Red Planet
Rosetta’s stunning Mars
Between the Devil and the deep Red Planet
Frosty blue dunes on Mars

CATEGORIZED UNDER: Astronomy, Pretty pictures

Comments (21)

  1. Larry M

    We never know what we might see? Like that giant scowling alien face just left of center in Wayne Jaeschke’s picture?
    Pareidolia? Me?

  2. rick

    Dont forget to mention how you can easily find Venus today in full daylight right next to the Moon.

  3. Stu Harris

    Glad you set us straight on the relative orbits of Earth and Mars. Believe it or not, the following sentence was actually published in a mainstream book in 2010:

    “Many of the planet’s orbits, which … should be perfectly circular by now, are highly elliptical. In fact, Mars’s orbit is so eccentric that its distance from Earth goes from 34 million miles at its closest to 249 million miles at its greatest.”

    The author? You guessed it –the error-prone Mike Bara.

  4. Oh, Professor Pierson, have you got a moment…?

  5. Chip

    Wonderful picture, and Ockham’s razor applies well here: Could it have been caused by an impact just over the Martian horizon? No bright flash or atmospheric changes. A volcano? There are ancient volcanoes but no new eruptions on Mars. A high altitude cloud? Yes – and a big one!

  6. Blargh

    My bet is the dust cloud from a fleet of spice harvesters…

    Seriously though, is there any chance of any of the satellites currently orbiting Mars having caught this?

    Chip: would the flash from an impact beyond the horizon really be detectable by telescopes on Earth? I kinda doubt it.

  7. Phil said:

    “Not that Mars is all that big; it’s 1/3 the Earth’s diameter and still 100 million km away!”

    Um … Wikipedia says that Mars is a little over 1/2 the Earth’s diameter, not 1/3.

  8. That “blob” seems awfully high to be an atmospheric phenomenom. Could it possibly be an impact?

  9. Messier Tidy Upper

    Incredible image and fascinating object here. :-)

    Bright, high up in altitude and latitude, not too long after some major solar activity – could it be a Martian aurora? Oh wait, no planetary magnetic field on Mars. Never mind.

    Hmm … If there was a meteor shower or meteor storm even over that spot could that be the dust from them burning up – but its far too localised and we’d see a brighter glow wouldn’t we?

    So, yeah, almost certainly a high altitude cloud on a mammoth scale and dizzying height.

    How does this compare with noctilucent clouds on Earth? Quite a bit higher in the atmosphere again I’m guessing?

    Spectacular and superb astrophoto – cheers! :-)

  10. Messier Tidy Upper

    @7. tracer :

    Phil said: “Not that Mars is all that big; it’s 1/3 the Earth’s diameter and still 100 million km away!”
    Um … Wikipedia says that Mars is a little over 1/2 the Earth’s diameter, not 1/3.

    From Phillips Astronomy Dictionary page 123 table of Mars stats :

    Diameter (equatorial) 6787 km
    Diameter (polar) 6752

    Nb. Brackets original.

    Versus for Earth, ibid page 61 :

    Diameter (equatorial) 12,756 km
    Diameter (polar) 12,714 km

    Again brackets original.

  11. Messier Tidy Upper

    Continued @7. tracer :

    Also on checking elsewhere :

    From Planets written by Carl Sagan, Jonathon Norton Leonard & the editors of Time life books (Time Life,1971.) page 131 :

    “It’s [Mars’es] diameter (4,220 miles) is a little more than half of the earth’s [sic], and its mass is about one tenth.

    Nb. Curved brackets original, square brackets added.

    Additionally a third source – Skywatching by David H. Levy (Kyodo printing Co, 1995.) notes of Mars on page 247 :

    Radius at equator (Earth =1) 0.53

    Putting that question another way. Again brackets original.

    Dr Robert Maddison confirms the earlier Martian figures in his A Dictionary of Astronomy, (Hamlyn, 1980.) providing on page 98, the rounded up figures of 6790 km for Mars’ equatorial diameter and 6750 for its polar diameter and Isaac Asimov in ‘Guide to Earth and Space’ (Ballantine books, 1991) writes on page 111 that Mars ” .. has only a little over half the diameter of the earth.”

    Hope this helps. :-)

  12. PS. Sorry, if that’s belabouring the point too much. I do get a bit carried away on occassion.

    Visual comparison of Mars and Earth size~wise (25 secs mark) among much more in the clip linked to my name here.


    “If we could transport Phobos and Diemos to our own Moon, they would fit comfortably inside the wide crater Copernicus with room enough for two moons of similar size.”
    – Stephen James O’Meara, page 102 “The Demon Sprites of Mars” in Sky & Telescope magazine, June 2001.

  13. Paul Laughlin

    Not sure at all but the bulge on Mars, isn’t that The Huge Volcano, Olympus Mons?

  14. vince charles

    6. Blargh Said:
    March 26th, 2012 at 1:48 pm

    “Seriously though, is there any chance of any of the satellites currently orbiting Mars having caught this?”

    We may see it in MRO MARCI (Mars Color Imager) images any day now. Some time later, there might be something in Mars Express HRSC data. Both may give height info, from stereoscopy.

    Of course, it’s also possible this feature is so thin, wide, and diffuse, that cameras won’t resolve it from close up except as a calibration issue. Then it would depend on Mars Express’ particular vantage point in orbit, I suppose. Or MRO catching a better shot of it on the Martian limb.

    The next step for the really inclined (and idle) would be to comb through Malin archives for the prior instances of high cloud.

  15. Green Tambourine Man

    What regions are we looking at in the first picture? I always have a harder time picking out places on Mars than on the Moon. And yes, I’ve already been to Wikipedia.
    If anyone can help, I’d be very grateful.

  16. @13. Paul Laughlin : “Not sure at all but the bulge on Mars, isn’t that The Huge Volcano, Olympus Mons?”

    Well kinda a part of it but only a relatively “small” part – the Tharsis bulge – see :


    Which notes :

    The Tharsis region on Mars is a vast volcanic plateau centered near the equator in Mars’ western hemisphere. The region is home to the largest volcanoes in the Solar System, including the three enormous shield volcanoes Arsia Mons, Pavonis Mons, and Ascraeus Mons, which are collectively known as the Tharsis Montes. The tallest volcano on the planet, Olympus Mons, is often associated with the Tharsis region but is actually located off the western edge of the plateau.

    The other huge volcanic plateaux is the Elysium one – see :


    There’s also a youtube fly over animation with more info here :


    Plus a good Youtube Mars clip by AggManUK linked to my name for this comment which has a bit on Olympus Mons and the Martian volcanoes starting at the 3 minute mark approx.

    That high altitude cloud feature, incidentally, is in the northern polar Vastitas Borealis region where (very roughly indeed!) the Phoenix lander landed and a long way from the Tharsis bulge which is roughly equatorial.

    Hope this is useful / informative / enjoyable for ya. :-)

  17. I wonder if the Phoenix lander* was still working what it might have seen of this mega high cloud? Hmm .. if there was something like this feature in the sky at the time could Phoenix have seen it?


    * Click on my name here for the Phoenix NASA homepage.

  18. Jeffersonian

    I always like pointing out Arcturus to people, then I tell them it’s in the asterism “Booty”. It’s , IIRC the 2nd brightest star in the Colo sky when Vega isn’t visible (but only visible from, what, mid-winter to mid-autumn?) so you can always find it.

  19. pat k

    Everyoned an astronomer huh phil

  20. Recent news item on this high-altitude, high latitude martian cloud is now linked to my name here – or search ‘Mars’ mystery cloud explained’ by Alan Boyle on the Cosmic Log blog posted 16 hours ago.

  21. @ ^ D’oh! Wrong link there. Oops. Okay take II this time should be right.


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