Vesta interest

By Phil Plait | February 17, 2010 1:32 pm

hst_vestaTonight, the 530 km (320 mile) wide asteroid Vesta is at opposition. That means that it’s opposite the Sun in the sky, so it rises when the Sun sets. That makes it easier to observe since you have literally all night to go out.

vesta_oppositionBut it also means it’s at the point in its orbit when it’s closest to Earth. Since it orbits the Sun in the main asteroid belt, about twice the distance of the Earth to the Sun, it’s at perigee (closest to Earth) when the Sun, Earth, and Vesta are all in a line. The diagram above I made using my awesome Photoshop skillz should help.

Objects that are closer are brighter (and at opposition we’re looking straight down the beams of sunlight shining on Vesta’s surface, so it’s like a full moon effect too), so tonight is just about picture perfect to look for the asteroid.

Even better, it’s the brightest asteroid in the sky! It’ll be shining at about magnitude 6.1 tonight, which is just barely visible to the human eye without aid, though binoculars will help. It’s in Leo, not far from the bright star Regulus. Go to Sky and Telescope for a map.

And if you happen to spot the tiny world, take a moment and think about this: the NASA mission Dawn will settle into orbit around Vesta next year, in 2011. The image I posted above is from Hubble, and is pretty much the best one we have from here on Earth. In late 2011 we’ll have images of it that will be sharp and clear, and, I’m quite sure, jaw-dropping. But until then, go out and take a look for yourself! If not tonight, then sometime in the next week or two.

Astronomy is really cool, but what makes it so fantastic, to me, is that you can go out and do it yourself. Go.

Image credit: Ben Zellner (Georgia Southern University), Peter Thomas (Cornell University) and NASA

CATEGORIZED UNDER: Astronomy, Cool stuff
MORE ABOUT: asteroid, Vesta

Comments (16)

Links to this Post

  1. How to photograph an asteroid | February 22, 2010
  2. On approach to Vesta | Support Constellation | June 13, 2011
  1. Jim

    We may have to revoke your pun privileges for this one. 😉

  2. “you can go out and do it yourself”

    Your right, this is awesome. It’s hard for normal people to every hope to see many things like the stuff that goes on inside the LHC, but anyone can see a lot of cool stuff doing amateur astronomy.

  3. Paul Clapham

    I did go out and do it myself last night, and I did actually manage to see Vesta. I had made a couple of tries before without seeing it, but this time (thanks to the two helpful nearby stars) I saw it. From the city with all its light pollution. With my birdwatching binoculars. In those conditions, magnitude 6 is about the limit of visibility.

    I almost missed it, though. I had read about the opposition a couple of months ago but thought “February? What’s the chances of a clear sky in Vancouver?” and basically forgot about it, until I went out to walk the dog and suddenly remembered it.

  4. Peter Laws

    OMG! When will it hit??? It’s bigger than the ones that killed the dinosaurs 6000 years ago!

    What shall we *do*?

  5. Off topic, but I knew you needed to see it:

  6. John Paradox

    you can go out and do it yourself. Go.

    In Other Words: DO try this at home.


  7. If the Earth-Mars opposition was a few weeks ago, and the Earth-Vesta opposition was last night, does that mean that the Mars-Vesta opposition is coming up soon?

    If so, are there any plans for HiRISE to try to take some pictures? It is twice as close as Hubble. Maybe I should ask Emily…

  8. bigjohn756

    But, will Vesta be as big as the full Moon like Mars is every August when it’s at perigee?

  9. Messier Tidy Upper

    So you got my email about this BA did you? Or was it somebody else or you spotted it yourself and just not-so chance co-incidence that I sent you that the other night and came to find it here today? Are you recieving my emails? Afraid I’m not sure & would love to have confirmation either way. Saying this here because I’m not sure how else to reach you – hope that’s ok.

    What happened to “tip of the asteroid to … ” type credits? 😉

    – StevoR aka Messier Tidy Upper

    PS. Having posting troubles again with my main email address. Was it something I said? :-(

  10. Pi-needles

    @ 4. Peter Laws Says:

    OMG! When will it hit??? It’s bigger than the ones that killed the dinosaurs 6000 years ago!

    2012! 😉

    No, not really. :roll:

    What shall we *do*?

    Redirect it to collide with Mars – that planet could badly do with some extra mass! Collide enough asteroids into the red planet and it will grow and perhaps become habitable if it gets large enough to kick start some plate tectonics and build up & retain an atmosphere. Yes, really – it’d be a handy start to terraforming it. 😉

    @ 8. bigjohn756 Says:

    But, will Vesta be as big as the full Moon like Mars is every August when it’s at perigee?

    Well it will be as seen from *somewhere* – just somewhere very close by and NOT from Earthican skies where it will be a “star like” point still. (Hence the word asteroid.) 😉

  11. DLC

    It’s as close to us as it gets != It’s gonna hit!

  12. Brian

    Pity we have 100% cloud cover here. I can’t see a thing.

  13. Grimbold

    Woohoo! I succeeded in seeing it though my binoculars. Having Gamma Leo and 40 Leo nearby makes it easy to spot.

  14. ozprof

    Hi BA,

    I am surprised at you, making such an elementary mistake!

    “But it also means it’s at the point in its orbit when it’s closest to Earth.”

    No it does not. Actually if you check out the distances and the time of opposition, they differ by several days. This is the normal situation. Opposition rarely coincides with closest approach. A good example is Mars, opposition and closest approach can differ by over a week.

    If all the planets were in circular orbits, then you would be correct.

    Been quite a discussion about this on the mpml board. You might find it enlightening.


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