A thoroughly sporadic column from astronomer Mike Brown on space and science, planets and dwarf planets, the sun, the moon, the stars, and the joys and frustrations of search, discovery, and life. With a family in tow. Or towing. Or perhaps in mutual orbit.


Sometimes I like to write about things in the sky that I've been studying. Sometimes I like to write about scientific discoveries in the outer solar system. Sometimes I even write about wild speculations I have about the solar system. But, every once in a while, I get to just sit back and watch the sky go by.

I love comets. When I first started graduate school to get my Ph.D. in astronomy, I wanted to study the most distant galaxies in the world. But my Ph.D. advisor really wanted me to start by doing a project studying a comet (actually, he wanted all  of his graduate students to start with comets, because no one stuck with them; they jumped to galaxies as fast as they could). I fell in love with comets. Mostly, I think, I fell in love with the fact that you could use huge telescope to study things in the sky that you could actually see with your eyes or with binocular or with a camera. Things that were real. 

So I was pretty excited  about the prospect of Comet Panstarrs close to the tiny tiny crescent moon tonight. We have a great western horizon from my house and I was pretty sure we would have good views. Scientifically, I have nothing at stake. I'm not involved in any attempts to look at the comet with telescopes big or small, on the ground or in space. I just wanted to see it.

So I waited.

The tiny crescent moon was going to be easier to see, so up and down, back and forth, with binoculars I searched. THERE! It was, 25 minutes after sunset, higher than I thought. This was good news. It would be a good ~30 minutes before the comet set. Long enough that even my daughter Lilah would be able to see it.

(Lilah uses a placemat every day that has astronomy pictures [including, yes, Planet Pluto. It was a present. Really] on it, including comets. She is really really excited about seeing one in real life).

I had set out the camera and tripod earlier, and started taking long exposures, hoping to capture the comet. I kept seeing something. Maybe. To the left. Where I knew it should. Be. But? Well? I dunno.

Until, finally, jackpot:

See it? Barely? Something like 6 lunar diameters to the left of the moon?

And, I should mention, that I spend much less time than I should staring at the thin thin thin crecent moon with binoculars. It was spectacular. And it is monthly. Missed it tonight? Go next month.

The moon and comet slowly set in the west, while the sky got darker. Here, now, are a series of pictures where I just got to be a sky tourist. No big telescopes, no data collection, just me, a telephoto, a camera, my family [yes! Diane and Lilah both saw it! They were both a little shocked that they could actually see a comet!]. Here we go.

I love the view out my backyard. Particularly tonight.

It got lower and lower (and in the traffic pattern of LAX)

I love the palm trees on the horizon. Yup. I live in LA.

Finally it set.

I'll try again all this week from Hawaii, where I will be for the 20th anniversary of the opening of the Keck Observatory. It will seem a little more like science, though. There is something magical about looking from your backyard and seeing a visitor from far far far far beyond the Kuiper belt. And a spectacular moon.

The last shot I got, before I had to take Lilah in, read her a bed time story, and pack for Hawaii, looks like this:

There's a lot of murk between us and the moon, and us and the comet. But, really, it's just another night here in LA, as the sky darkens, the stars come out, and the world bustles underneath.


  1. Thanks for the pictures! Were these taken at different exposure settings (or at least the first different from the last three)? I think the first picture brings home the fact clearly how tough it is to spot it. All those 2-3 sec exposures that I've been looking at in the web have fooled me into thinking that it was fairly easy. Two evenings with binocs, and one with a Moon a few degree away, haven't helped so far. :(

  2. I could see it naked eye, but only after I first found it with the binocs and knew exactly where to look. It was tough. There are .5-2 second exposures. And clearly I need a more stable tripod!

  3. What a gift! Thanks so much, Dr. Brown...

  4. That is a very nice back yard view (and comet)!

    For exposure, I recently tried to calculate how fast the sky moves in pixels/s if you use a tripod without tracking for an object near the ecliptic:

    pixels/s = f * Rx * pi / (43200 * d)

    where f is the focal length in mm, Rx is the horizontal resolution in pixels, and d is the horizontal width of the sensor in mm (36mm for full frame).

    For a 300mm lens on micro four thirds (or 600mm on full frame), this results in about 5 pixels/s, so you'll get motion blur if you go much above 1/5 second exposures.

  5. It's just fun to imagine how many of us were out that night, like a wave across the US as the Earth tuned and we came to sunset with that lovely young Moon. I was in the best local west view....a WalMart parking lot...with some folks who meant to be there and some who wandered over wondering what we were looking at. Enjoy the view from Hawaii, I envy that, we're rained out here in Nashville for several days.

    Tripod, yes, and two second delay if you can...I've found most of my jitter was at the button push. :-)

  6. Dear Mr. Brown:

    I did not know that you lived in "Smog Angeles," although it has balmy weather throughout the year, it also has a lot of air and light pollution which are obstacles to clear viewing of the heavens. As an Angelino, there is access to some great astronomical assets within an hour's drive including Griffith and Mount Wilson Observatories and JPL; the latter two I am eager to visit.

    Comets are the unsung heroes of the Solar System, as they may have brought water and perhaps life in the form of organic molecules, amino acids or even simple (micro) organisms to Earth.

    Comets also may bring destruction as in the case of the infamous Tunguska event in 1908 where perhaps a comet slammed into Siberia with the force that was 1,000 times greater than the nuclear bomb that the U.S.A. dropped over Hiroshima, Japan during World War Two.

    Where do comets come from, perhaps the Oort cloud if such a place even exists? If comets that are made of water ice pelted the Solar System billions of years ago, then why is water (in any form) not much more common, i.e. it should be (abundant) on most rocky worlds from Earth/Moon to the Oort cloud, but it is not, why?

    P.S. Please give us a head's-up at least several days in advance, next time a special event like the comet you wrote about along with instructions regarding how to find it.

    Thank you.

    1. G. Smith....

      Special events like comets are publicized in so many places...we want Mike to stay busy finding more cool stuff in the outer solar system!

      Sky and Telescope's page on what is out this week, Astronomy magazine, Universe Today, this particular comet has been anticipated since last fall. Your local astronomy club is also a great resource. Your local planetarium. If you want to know more about fun visual events in the night sky, there are numerous ways to find out. Amateurs are already observing C/2012 S1 (Comet ISON) with telescopes, we hope it will be so bright you can't miss it in the sunrise AND sunset skies in November and December.

      Not only are there lots of great places to find out how to observe ephemeral events, many also include the science involved as well. And I haven't even mentioned computer planetarium programs, your smartphone, etc that can produce custom views for your exact location.

      Enjoy the sky! If you have clear weather, you can still find this comet in the sunset.

      Theo Wellington
      Barnard-Seyfert Astronomical Society / Nashville
      Sudekum Planetarium / Nashville

  7. Nice photos,..we had bad weather in the most part of Europe these last weeks,..so I wasn[t successful in observing ,..but here are some the oldest known depiction of comets from China,...https://www.google.sk/search?hl=sk&site=imghp&tbm=isch&source=hp&biw=1280&bih=575&q=mawangdui+silk+comets&oq=mawangdui+silk+comets&gs_l=img.3...1096.7984.0.8223. Pavel

  8. here is also published theory how big world plagues were tied with arrivals of comets to perihelia,...probably old viruses,...from comets are responsible,...so not only impacts of fragments but also old preserved microorganisma could trigger some catastrophe,.. http://journalofcosmology.com/Panspermia10.html

  9. NASA wants to prove existance of extraterrestrial primitive or advanced life, but we actually have such proofs for microorganisma,...it is publised also in that mentioned web page

  10. NASA wants to prove existance of extraterrestrial primitive or advanced life

  11. Anno 2013, which object is considered to be the furthest in the solar system?
    Is it 1000 Km large Sedna (518 AU and 12000 years orbit) or small 150 Km 2006 SQ372 (1500 AU and 22500 years orbit)?