A marvelous night for a Moon (and Mars) dance

By Phil Plait | January 30, 2010 9:17 am

Were you out last night to see the Moon and Mars together? It was a lovely get-together! I took some pictures, and here’s the best one:

Mars is the reddish "star" to the left of the Moon. A couple of actual stars are visible as well, and the pink blob on the left is a reflection of the Moon inside the camera.

Funny, you can barely see Mars in the picture, but it was really obvious by eye. That’s because cameras see things linearly — an object twice as luminous as another will appear twice as bright in a picture — while our eyes see things logarithmically — a mathematical function that lets our eyes see a much larger range of brightness based on multiplication, not addition. It’s actually a bit more complicated than this, but the point is while to the camera the Moon was vastly brighter than Mars (about 30,000x as bright!), to my eye the difference wasn’t nearly as much (only about 10x as bright). This allows our eye to detect faint and bright objects at the same time, which a camera can’t do easily.

You may have read that the Moon looked so bright last night because it was at perigee, the point in its orbit when it’s closest to Earth. Honestly, that makes no difference to the casual observer. While it really was a bit bigger and brighter, the difference over a normal full Moon is pretty small, and you don’t have anything to compare it with. If you could have superimposed a normal full Moon next to the Moon last night you might have seen a difference, but with just the one Moon sitting there you’d never notice.

This reminds me of the time in 1999 when people said the perigee full Moon would be so bright you could drive at night without headlights! Yeah. Bad idea.

But I do hope that some of the hype got people outside and noticing the sky. It’s amazing what you can see, what lovely things await you, if you simply look up.

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures
MORE ABOUT: Mars, Moon, perigee

Comments (40)

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  1. This Year’s Biggest Full Moon « thcpress.com | February 1, 2010
  1. Messier Tidy Upper

    I do hope that some of the hype got people outside and noticing the sky. It’s amazing what you can see, what lovely things await you, if you simply look up.

    How true & totally seconded by me. :-)

    Mars is the reddish “star” to the left of the Moon.

    Mars *is* indeed a “star” as are all the other planets except Earth*.

    A “wandering star” or “planete” in (ancient?) Greek or so I understand! 😉

    ! I took some pictures, and here’s the best one

    Great to see you doing – & posting here – some actual star-gazing and astrophotography yourself BA. Love it! :-)

    Even if as usual photos don’t quite do the moment and the view full justice. (Not meaning your photo in particular here BA, but pretty much all & any photos generally.)

    Is it true what I read somewhere that *professional* astronomers rarely look up at the sky themselves and cannot recognise the constellations and planets seen in person in the night sky? I hope not!

    How often do you, Dr Phil Plait, personally get to just star-gaze and enjoy the heavens? has this changed much over time?


    * Of course, Earth is really a “wandering star” too – but we don’t see it “wander” because we’re on it and thus it *appears* to be standing still && the sky *appears* to be moving from our frame of reference. From another planet that planet would appear to be the stationary “centre” & every other planet a “wandering star.” But then y’all know that don’t you? Hope I’m not belabouring the obvious too much. My apologies if so.

  2. JenniferBurdoo

    That last is exactly what I’ve been telling people! I’ve been experimenting with my Galileoscope all last week (last night I didn’t, there were scattered clouds) and I’ve actually had a couple neighbors stop and look. This tactic worked better when I was in college and there were more people wandering around in the late evening, but it’s a lot of fun to just… well, “show off” the sky.

    Thanks for advertising the Galileoscope on here, by the way. It’s getting me outside a lot more lately.

  3. Ld Elon

    Its wasnt as good as last week when the spy/chopper got nearly struck by incoming projectilous, hehe
    I need know Man to tell of the wonders of the sky at night, we have those of the sky at night to tell us that.
    Ive seen many fantasic sights over the last few years, and they as they are, gather pace. ‘too show us’

  4. Ld Elon

    oops i made another typo booboo.

  5. DrFlimmer

    I had only very short glimpses at the pair. Far too cloudy over Germany. And way too much snow 😉 (cannot remember having so much snow over such a long time in the “Ruhrgebiet”).

    Too bad.

  6. Jya Jar Binks Killer

    Off topic, sorry -and even sorrier about the glum note this is introducing – but I’m very concerned & angry about the rumoured (now seemingly confirmed?) NASA funding cut & abandonment of the “Moon & Beyond” Ares-Constellation space program:

    Have you heard any more about what’s happening with that?

    Has anything been officially announced on the fate of the US manned space program yet – will you tell us more soon & keep us updated, please BA?

    I have always hoped – &, quite frankly, impatiently *expected* – to see in my lifetime Humans landing again on the Moon & setting up a base there and making that long dreamt of first landing on Mars and some asteroids and hopefully more too.

    But now, well, I’m starting to wonder where it all went wrong and if I’m watching the end of Human space exploration instead. Or, at least, the end of the United States humans-in-space program for the forseeable future. :-(

    I hope to FSM & blazes it ain’t so. Please tell me it isn’t!

    But BA, please do let me know what’s happening; if there’s been any new developments and please give us all your thoughts on what this means and whether there’s anything we can do to change the situation here for the better & lobby for some sort of men back to the Magnificent Lunar Desolation (& women & scientists eg.astronomers too!) program and on to Mars and more.

  7. When I started stargazing I was just dumbfounded by how many of the deep sky (mostly Messier) objects I could see with the naked eye, once I knew where to look and how. I was a little ashamed, then, that I’d never spent enough time out under the stars before then to realize that.

  8. Jeremy

    On the 28th, a pretty awesome moon halo was around for several hours in Los Angeles. When I showed it to my 70+y.o. landlords, they said they had never seen anything like that in their entire lives….must not look up very often.
    My pictures certain didn’t do it justice.

  9. Evilhick

    I’ll show my age here.

    When you wrote .

    “It’s amazing what you can see, what lovely things await you, if you simply look up.”

    My mind read in Jack Horkheimer — Star Hustler voice .

    He always said. ” Whatever you do …. keep looking up . ”

    This is a compliment . I was in my teens when this guy use to come on TV at night ( on PBS ) . We would run outside to find the things he was talking about .

    His intro went something like :

    Some people hustle , some people hustle cars Jack Horkheimer — Star Hustler hustles STARS .

  10. Jya Jar Binks Killer

    @ 4. Ld Elon Says:

    oops i made another typo booboo.

    Er, you do know we have an edit facility here and can correct such typos right? Just click on your comment when it says “You may click on your name and/or comment to edit.” with a timer countdown in a black scroll and you have about 15 minutes to correct your post.

    @ 3. Ld Elon Says:

    Its wasnt as good as last week when the spy/chopper got nearly struck by incoming projectilous,

    What the … ?!

    You have *got* to tell us what that’s all about!

    Oh & “projectilous”? Would that be the typo then? 😉

  11. Luke

    I live in Arizona, US and it was clear skies last night and the moon was crazy bright. It was cool. Didn’t notice mars.

  12. Crummy weather in the southeast right now, so I missed it last night. Might get a break tonight, definitely tomorrow night. It’ll be cold then. I hate winter here, it doesn’t even SNOW for the love of pete. Just gets cold enough to make you not want to go outside. I’ll stop complaining now. :)

  13. Pi-needles

    This reminds me of the time in 1999 when people said the perigee full Moon would be so bright you could drive at night without headlights! Yeah. Bad idea.

    Well you *can* drive at night without headlights then or during any phase of the Moon for that matter.

    You just won’t get very far before you crash! 😉

    That “Bad idea” bit is 100% right though. 😉

  14. Messier Tidy Upper

    @ 6. Jya Jar Binks Killer :

    I expect the Bad Astronomer will keep us informed & hope he’ll post more on that soon.

    However, I hate to say it but the news as seen online via yahoo (Australian website) today is sounding pretty bad :


    The “headline part” of the link there says it all really. I’m terribly sad and upset by this myself. :-(

    I also posted that same link on this more appropriate BA blog page for discussing the rumours (now more than that it seems) of the Ares-Constellation program cancellation :


    Where you possibly might find more updates from other ppl incl. the BA – or not.

    Lets keep the discussion on that issue there & not “gloomy-down” this “brighter note” thread shall we please?

  15. Hi, people. If you want to see it from the Southern Hemisphere perspective, see the picture I posted in my new blog. It was a beautiful view as the two rose over the mountains and lake Nahuel Huapi. At the bottom of the post there is a comparison I made last year of the perigee and apogee full Moons. (The blog is in Spanish, pictures are clickable). Here: http://guillermoabramson.blogspot.com/2010/01/no-marte-no-es-grande-como-la-luna.html


  16. Jya Jar Binks Killer

    ^ Sure. No threadjack intended. THX.

  17. Flying sardines

    Mars is the reddish “star” to the left of the Moon. A couple of actual stars are visible as well, and the pink blob on the left is a reflection of the Moon inside the camera.

    So .. the Moon is NOT a vampire Moon then?! 😉

    What are the other actual stars that are visible there – can you name them?

  18. Levi in NY

    Indeed, our eyes’ capacity to detect objects of different brightnesses is amazing. Last night was cloudless here, and I was able to point out the Moon and Mars (and Orion and Sirius) from the middle of a very brightly lit parking lot. No camera would have seen more than just the Moon.

  19. I was out in the full moon last night in Colorado, about 50 miles from where Phil lives, and let me tell you–after my eyes adjusted to the darkness it was really bright out. Shadows were crisp and noticeable, and I could see pretty much anything I needed to in order to navigate. Indeed, I think that it would be perfectly safe to operate a car with that amount of light without headlights, assuming that nobody else was using headlights and there were no bright lights in the area to mess up my night vision. In fact, I think that if I were out on a country road in the middle of nowhere, it would be more safe to drive without lights (assuming I gave my eyes enough time to acclimatize to the dark) than with lights on–because you can see a larger area of what is around you. But in an urban or suburban or even semi-rural area, it would be recipe for disaster.

  20. Sili

    and the pink blob on the left is a reflection of the Moon inside the camera.

    Don’t be silly! That’s just what they want you think!

  21. sophia8

    TsarBomba@19: Please don’t try driving without lights even a rural area! Where I live in Scotland is very rural, with no road lights, and it’s almost like daylight when we get a Full Moon in a clear sky (like it is right now). However, not everybody around here drives and lots prefer to cycle or walk if they’re not going far.
    In bright moonlight, it’s easy enough to see the road ahead, but not at all easy to see what’s in the shadows. People tend to walk at the side of the road, where the shadows are (we have lots of trees here), and without headlights you often can’t see them until you’re just yards away. When you’re driving a car, a couple of yards is way too late to stop.
    So keep those headlights on!

  22. Kevin

    Here where I live it’s been cloudy nearly all month. Oh sure, we might get a peek at the Sun during the day, but it always clouded up at sunset. I didn’t get a chance to do any observing this month.

    However, yesterday afternoon the skies cleared, and it was beautiful out. I went out and shot the Moon & Mars together in the evening, then again around 1am – where I got a great Halo shot – and tried at 4.30am, but by then some clouds ruined the view.

    Full Perigee Moon – http://bit.ly/9tkDOq
    Moon and Mars – http://bit.ly/cU17xf
    Lunar Halo – http://bit.ly/94P50h

  23. Michel

    We are having clouded nights for the last two months.
    Ah well, at least the scope is nice to look at.

  24. Gary

    It was a beautiful night here in Florida on the night of the 28th. There was a halo around the moon, and I was able to take a picture. You can see Mars in the halo at the bottom of this picture, and a vapor trail from a plane intersecting our view of the moon.


  25. Dan Breslau

    Nice photo!

    I could be off-base here, but I think there’s a simpler explanation for why the Moon doesn’t outshine Mars so much in the picture: There’s only so much white that you can put on a piece of paper, or on a computer screen.

    A photograph showing just the Moon shows a white disk with some darker regions (the mares and shadows.) To get Mars in the picture, you probably needed a longer exposure, and/or a larger f/stop, than you’d use to shoot the Moon by itself. But this doesn’t make the Moon noticeably brighter; its highlights would already have been as bright as they could get. It does wash out the darker regions, so that all we see is a white disk. It also gives the Moon more of a corona. But it can’t really make the Moon much brighter than it looks when it’s exposed normally.

  26. Brian Mingus

    Phil I think you are wrong about not being able to perceive the moon as brighter. I had no idea the moon was at perigree last night and my girlfriend and I stared at it for several minutes in awe of its amplified brightness. Cheers from Boulder.

  27. Living the Pacific West Coast, when I look up I see clouds and rain.

    Every night this past winter when there has been something really cool to observe with naked eye, it rains.

  28. Melanie (Australia)

    Was great to get out and view Mars. Looking up helps give perspective…big sky, small mozzies carrying me away!

  29. Katharine

    “A marvelous night for a Moon (and Mars) dance”

    As the Romanians say, hop, hop, ş-aşa.

  30. Jeff

    I did know beforehand that it was supposed to be an especially bright moon, so I may have been biased somewhat. However I too thought that the moon was amazingly bright (San Francisco area) when the clouds happened to part enough to get a clear view last night. I actually had to squint to see the darker areas of the moon, since at first it just looked like this uniformly bright disc. I don’t remember that ever happening before for me.

  31. Brian Mingus

    Jeff, same here! Brightest moon I’ve ever seen. And once I was able to resolve some detail the only visible features were those of the face of the “man”.

  32. Tom

    I took a few photos too, and posted the best here: http://bit.ly/aMu5R0
    It was my first attempt at photographing the moon and I’m pretty pleased with it. Here’s to an unexpected cash windfall so that I can get some better equipment!

    My girlfriend says mine’s better than yours, but it’s part of her job description to say so…

  33. I got the Moon and Mars inside a ring as well from here in Tucson. http://bit.ly/9NEpNH

  34. Is this when Mars is supposed to look as big as the moon?

    – Jack

  35. HAnnu Siivonen

    Too bad it’s not possible to get good picture of both Moon and Mars (or even Venus) at once. Or is it?

  36. Curt

    Phil, I made a few tiny improvements to your original photo.

    If interested, it’s here:


  37. FoxtrotCharlie

    I had a nice seat in a neighbor’s front yard when we were having a barbecue (around Midnight). When the Moon and Mars were at their zenith it was very much a 2001 moment. The sky was devoid of clouds and the Moon was showing off this large halo of light around it (that’s one very bright full Moon). This halo was large enough to contain both Mars and the Moon within it… all I needed was Requiem and a Monolith.

  38. Aerimus

    My 3 1/2 year old daughter went out a couple of nights ago (before the rain moved into Atlanta) and looked at the moon and mars in her Galileoscope [mount on a tripod], and I also pointer out Orion and Sirius to her. It was quite cute when she cam in and told the wife that she saw “the Moon, an orange planet star, and a Doggie star)

  39. Chris Sol

    Yes, I saw it (first time I’d seen Mars). It was lovely – thanks for letting us know :)

    (PS – I even got to see its “diameter” with the tiny telescope I have, 3 inch or something!)


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