Venus rounds the corner

By Phil Plait | March 22, 2012 7:38 am

If you’ve been outside after sunset the past few weeks, there’s not much chance you’ve missed Venus shining like a laser in the west. It’s obvious enough anyway, but the conjunction (close pass) of Jupiter really made this a sight to see!

And as lovely as it is to look at with the eye, Venus is starting to get interesting through a telescope now as well. Venus has phases, just like Moon. It orbits closer to the Sun than we do, so sometimes we see it on the far side of the Sun, and sometimes it’s between us and the Sun. When it’s on the other side of the Sun we see it fully illuminated, and as it gets between us and the Sun it appears as an ever-thinner crescent. Hopefully the diagram here will help (click to embiggen).

Right now, Venus is just "rounding the corner" of its orbit; the past few weeks it’s been heading away from the Sun from our viewpoint, and very soon will reach its greatest elongation in the sky from the Sun. At that point, every day will see Venus get a bit closer. Right now, Venus is very close to being half full.

"Amateur" astronomer Emil Kraaikamp observed Venus on March 15, and took this very nice shot of it:

Venus is shrouded in clouds, making it relatively featureless when you look at it through a telescope. However, if you use a filter that lets in ultraviolet light, some faint and subtle features in the clouds can be seen. Emil’s picture did just that, using a UV filter plus one each of red, green, and blue to get a true color plus UV picture. The phase of the planet is obvious enough, and you can also spot some of the patterns to the clouds, too.

Another astrophotographer, Alan Friedman, also took a stab at Venus (this time on March 17) and got the picture shown inset here. Again, you can see some detail, but clearly it’s not easy to get the goddess of love to reveal her secrets!

Venus reaches its maximum distance from the Sun in our skies on March 27. After that it starts moving closer to the Sun. It’s not physically getting closer to the Sun, it’s just moving between us and the Sun, but to us when we look at it in the sky we’ll see the two getting closer together.

But in physical fact Venus is getting closer to Earth, so even as it becomes a thinner crescent it will be getting bigger and bigger as our distance narrows, making it a great target even for binoculars. This means it will be getting even brighter in our sky! So if you think it looks like a beacon glowing to the west now, just wait a few weeks.

… and then the most amazing thing will happen: Venus will pass directly across the face of the Sun! This is an incredibly rare event. These transits, as they’re called, occur in pair separated by 8 years, but each pair is separated by more than a century. The last one was in 2004, but the next won’t be until December of 2117!

I’ll have more info about this event soon. The transit happens on June 5/6 2012, so you might want to make space in your calendar. Odds are pretty good this will be your only chance to ever see it again.

Image credits: Emil Kraaikamp; Alan Friedman, used by permission

Related Posts:

Galactic arch over the conjunction
Paradise above and below
Pic of pairs of planets and people
Juspiter and Venus still blaze in the west

CATEGORIZED UNDER: Astronomy, Cool stuff, Pretty pictures

Comments (24)

  1. Kevin Wakley

    On Monday evening I took an early evening flight, with clear skies. As the plane banked I suddenly saw Venus with Jupiter below it. I’ve often wondered how people could mistake Venus, an object static in the sky, for an extraterrestrial spacecraft. I now no why! As the plane banked, with no objects around to give perspective to what I was seeing, it really seemed as Venus and Jupiter were passing the plane! Eerie…

    I’m hoping the skies are clear at the weekend so that I can see the triple conjunction of Venus, Jupiter and the moon!

  2. FMCH

    Funny this, I was a little saddened thinking that my great great grandchildren would be seeing this event 2117. It really puts into perspective just how long astronomical timescales are.

  3. Chris

    Actually Venus just passed it’s perihelion a few days ago on March 20th. So you are correct Venus is in fact moving further away from the sun, at least until July 11th.

  4. Daniel J. Andrews

    The transit happens on June 5/6 2012, so you might want to make space in your calendar. Odds are pretty good this will be your only chance to ever see it again.

    There’s an understatement. I’d say the odds are extremely supremely good that if you miss this one, you won’t see another ever, unless you plan on living to 12o+, or perhaps being in outer space on some space craft.

  5. “Corners!?” For a planetary orbit?! What’s the Cytherean orbital eccentricity and explanation for that!? 😉

    Always thought Venus had one of the most circular & lowest eccentricity of all planetary orbits.

    Great images. :-)

    Unfortunately here, it’s been pretty cloudy last few nights so haven’t seen much of it. Nothing quite like seeing Venus at its brightest though.

    PS. The answer to the question asked in the title of the music linked to my name is, memory serving, minus four point four at its peak luminosity. 😉

  6. In my 240×254 monocular, Venus looks left right reversed. But it’s really upside down and backwords (or rotated 180 degrees). I should look again in 10×50 binoculars. Or from south of the equator.

  7. Phil H.

    How bright would a full Venus be from the surface of Mercury?

  8. ntsc

    Been noticing the pair at night. Perhaps haul out the scope tonight

  9. Kelly

    @Kevin Wakley, imagine how much brighter Venus would be in a part of the world (or a time gone by) with little or no light pollution!

  10. chief

    I pulled my scope out monday and did a “show” of Venus, Jupiter and Mars. Too bad saturn is not yet up earlier. Been waiting all winter.

    Once things settle down here, I’ll have to take a long look at getting some decent images, but still learning the software ins and outs of putting together stacked images and getting some pics to post.

  11. CB

    Stupid trees block my view of Venus (and recently Jupiter).

    Guess I’ll have to leave my driveway. It’s just such a shame for one of the few objects that you don’t need dark skies for!

  12. CB

    @ MTU

    That’s why it’s rounding the corner because the corner is round… and continuous… :)

  13. Ken

    If I’m reading the ephemeris right, on March 26 the Moon is going to pass between Venus and Jupiter. Geocentric RA/DEC at 00:00 UTC from the NASA ephemerides:

    Mar 26: Venus 3:13:01/+21:03:29, Moon 2:38:45/+17:37:58, Jupiter 2:38:44/+14:32:25
    Mar 27: Venus 3:17:02/+21:23:29, Moon 3:27:44/+19:56:10, Jupiter 2:39:34/14:36:30

    Would someone with better software like to refine this?

  14. Victor Bogado

    In the news tomorrow and on emails for the next few decades:

    Venus will appear as big as the moon in the sky tomorrow, see the graph on Phill Plate’s site.


  15. Grand Lunar

    I was wondering just where in relation to us where Venus was.
    Thanks for the info!

    And to imagine it’ll get brighter!
    Already it matches some of the planes I see at night.

    Venus and Jupiter sure make for a lovely pair.
    I wonder when this conjunction will happen again.

    A side note; Mars is also up in the east!

    Be even better if all the naked eye planets were together in the sky at once….

  16. Time to terraform the goldarned thing, already. Let’s go find some huge ball of ice out in the far reaches of the solar system and slow it down so it’ll head for Venus, along a winding trajectory that slows it down a lot before it gets there, then dump it in. Make sure it has a lot of nitrogen beforehand. Do the same for Mars, and the Moon. For Venus we’ll need a big sun screen, and for Mars a lens or mirror. This should put everyone to work for several centuries, and in the end we’ll have useful real estate, so that we can clean things up here and leave the original ecosystems in peace.

  17. Messier Tidy Upper

    @ ^ Jess Tauber : Yes! I’d love to see , well atleats a starton terraforming planets esp. venus inmy lifetime although its going tobe an exceptionally diffcult task.

    We’d need an impact enough to blow off a sizeable portion of the Cytherean atmosphere and restart its rotation and cooling and keeping Venus reworked cool – preventing it from overheating again will be difficult. Plus Venus has lost much of the water it started with due to the photodissociation of H20 and consequent escape of hydrogen into space from the Cytherean atmosphere.

    Many here will be familiar with Kim Stanley Robinson’s Mars trilogy books but I wonder how many are aware of another great novel trilogy on the terraforming of Venus? Written by Pamela Sargent these are ‘Venus of Dreams’, ‘Venus of Shadows’ and Child of Venus’ and ones’ I’d definitely recommend.

    Ideally, I’d like to swap the positions of Venus and Mars in our solar system – smaller Mars would be kept warmer but not smothered by a dense atmosphere, Venus further from the Sun would be warmed by its thick atmosphere and so wouldn’t freeze as Mars has. If only our solar system had worked out slightly differently. Or maybe we were extremely lucky? A bit beyond us now – we’d need the largest teleporter imaginable or a very careful set of orbital juggles to swap them now! 😉

    @12. CB :

    @ MTU – That’s why it’s rounding the corner because the corner is round… and continuous…

    Yep. Fair enough. I was half asleep (maybe even two thirds so) when I posted that last night and thus forgot that corners don’t necessarily *have* to be square! D’oh! 😉

  18. Jeeves

    Every time I see Venus up there blazing away I think of how bright the Earth must look from Venus. A full Earth at opposition must be a sight to see.

  19. Jackie

    The astronomy club I belong to already has an outreach event planned (at a local state park) for the transit in June. Can’t wait!

  20. Stuart Greig

    @9 Kelly
    I can tell you that from Norway it is ridiculously bright at the moment!

    Just been and checked the transit times for June:
    in progress at sunrise – OK not so bad,
    04:36 – again not so bad,
    wait that’s in UTC so shift it by two hours… 02:36,
    might have to be a late night session rather than an early one. Heading to bed after the sun has risen!

  21. Infinite123Lifer

    That’s what’s up. +infinity

  22. The next transit of Venus across the face of the sun won’t be until 2117.

    I hope that by the end of my lifetime, it won’t MATTER, because everybody will have personal interplanetary space ships and can view Venus from whatever angle they please.

  23. Jeffersonian

    Wait, I thought Venus looked brighter when it was more luminous (when it was reflecting sunlight instead of when it;s close and we are looking at its dark side) but you’re saying brightness is a function of proximity regardless of luminosity? I’m confused now.

  24. dcsohl

    Brightness depends on three factors: a) how far is the object from the light source (the sun); b) how far is the object from the viewer (the earth); c) how much of the object is illuminated from the viewer’s point of view (the phase).

    For an object in a roughly circular orbit like Venus, you can ignore (a) and collapse b and c into a single factor, namely, “what is the apparent area of the illuminated portion of the object?”

    As Venus draws closer to solar conjunction, it is getting closer to us and thus appearing larger (though only noticeably so when viewed through a telescope). At the same time though, it is turning into an ever-thinner crescent. For a while, its approach will more than cancel out the waning of the crescent, and the apparent area of the illuminated crescent will grow and thus it will grow brighter. (Not a lot brighter, but brighter.)

    The speed of its approach will slow, however, although the changing of the phase will not; it will even accelerate. So the factor making it brighter (distance) will be cancelled out and more by the factor that would make it dimmer (phase). So around May 4, Venus will start to fade. But until then…


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