A Daring Pairing of Moon and Venus

Early risers in North America are in for a treat on the morning of Wednesday, April 22nd, when the waning crescent Moon passes in front of the brilliant crescent Venus.

Tracks for Venus occultation
The apparent path of Venus behind the Moon on April 22, 2009, depends on where you are. The local horizon is approximately downward; celestial north is to the upper left.
Sky & Telescope
For much of the continent the occultation happens after sunrise in broad daylight. If the air is clear you can find the thin, dim Moon about 33° to the upper right of the early-morning Sun, with Venus near its edge. Sadly, this event will be a near miss along the Eastern Seaboard.

I'm tempted to hop a westbound plane, because in the Far West the occultation happens during morning twilight — with the Moon and Venus shining beautifully before sunrise but very low above the eastern horizon. When the Moon covers Venus they'll be only 6° up as seen from Los Angeles, 4° from San Francisco, and 6° from Seattle. When Venus reappears at these locations the Moon will be about 10° higher, with the Sun already risen or nearly so.

Because the Moon is waning, its bright edge will be the one that covers Venus and its dark limb will uncover it, as shown in the diagram above. The thin crescent Moon will be only 9% sunlit, while Venus (40 times smaller) will be a 17% crescent.

At locations where the sky is still fairly dark, all you'll need are your eyes to watch this celestial spectacle. You'll probably need binoculars or a telescope where the sky is bright. Because of Venus's significant angular size, its disappearance and reappearance will each be gradual, taking 30 seconds or more.

You can gauge the approximate times of Venus's disappearance and reappearance at your site using the maps below. Interpolate between the red time lines to get the Universal Time of the event. Along the graze line, you'll see the Moon's southern limb skim Venus but never quite cover it. The maps also indicate whether your location will be in twilight or daylight at this time. (You can get customized predictions for several hundred cities and towns here.)

Maps of Venus's occultation
Use these maps to estimate the Universal Times of Venus's disappearance and reappearance during its occultation by the Moon on April 22, 2009.
Sky & Telescope diagram

And if you're willing to get up a few hours earlier, you might be treated to a nice smattering of "shooting stars" from the annual Lyrid meteor shower. In most years you'll see fewer than 20 Lyrids per hour before the first light of dawn even under perfectly dark skies. But some years have brought outbursts of up to 90 per hour. Will 2009 be one of those?

Click here to check out the prospects for all of 2009's best meteor showers.

20 thoughts on “A Daring Pairing of Moon and Venus

  1. Grant Martin

    “You can gauge the approximate times of Venus’s disappearance and reappearance at your site using the maps below.”

    The maps were not included in the article.

  2. Grant Martin

    “You can gauge the approximate times of Venus’s disappearance and reappearance at your site using the maps below.”

    The maps were not included in the article.

  3. Grant Martin

    That’s strange — as soon as I posted my comment, the maps magically appeared! Never mind.
    For some reason, my post appeared twice, but I only clicked once.

  4. Grant Martin

    That’s strange — as soon as I posted my comment, the maps magically appeared! Never mind.
    For some reason, my post appeared twice, but I only clicked once.

  5. Dennis Worley

    I saw a Moon/Venus occultation in Cape Town on Jan 20th, 2007. A wonderful sight. Comet Mc Naught was also on show that evening!

  6. Ganesh

    What about India and other asian countries? Im in Chennai, India. Will i be able to see the great event?

  7. Recon

    Am looking forward to this … but with one slightly creepy memory attached. There was a brilliant occultation of Saturn on 10 September 2001. I shot some pretty sorry photos but one guy on my astronomy list (no longer exists) shot so excellents ones. The occultation was soon forgotten as I watched the very early news the next morning. I awoke to the news poeople showing one of the twin towers on fire … and my comment: “That’s why I would never work in a high-rise!” Later on I saw the second plane apporach and impact. “Now THAT wasn’t an acctident!”

    Hope nothing spoils this one.

  8. Recon

    Am looking forward to this … but with one slightly creepy memory attached. There was a brilliant occultation of Saturn on 10 September 2001. I shot some pretty sorry photos but one guy on my astronomy list (no longer exists) shot so excellents ones. The occultation was soon forgotten as I watched the very early news the next morning. I awoke to the news poeople showing one of the twin towers on fire … and my comment: “That’s why I would never work in a high-rise!” Later on I saw the second plane apporach and impact. “Now THAT wasn’t an acctident!”

    Hope nothing spoils this one.

  9. recon

    I only clicked once, also. But two appeared. We’re getting “reflections”. N ow I will click on “Submit Comment” and see if it comes up with only one, or two?

  10. recon

    I only clicked once, also. But two appeared. We’re getting “reflections”. N ow I will click on “Submit Comment” and see if it comes up with only one, or two?

  11. Jack

    Looking forward to seeing this during an early morning run with friends! The article states “The thin crescent Moon will be only 9% sunlit, while Venus (40 times smaller) will be a 17% crescent.” Considering the alignment of the Sun / Venus-Moon / Earth, how can this be? Assuming not a typo, is it Venus’s atmosphere that adds the extra illumination?
    Single-clicking “Submit Comment”…

  12. Kevin B

    At about the same time I have the occultation, the Lyrids, as well as two different Iridium Flares that I am going to try to take pictures of. Although the occultation will probably be far too low on the horizon to get a decent image.

  13. JC

    WOW – when I received my April issue of S&T, I could see that my home (near NASA-JSC) might be near the graze line so I checked with Occult 4.0 and lo and behold, it was! In clear skies with 20×80 binoculars, I watched the Moon lop off ONE of Venus’ horns from my driveway – very cool!

  14. JC

    Wow – simply stunning! I watched the Moon graze Venus this morning. The Moon appeared to lop off only one of Venus’ horns through my 20×80 binoculars from my driveway (~10 miles from NASA-JSC). My first “graze”!

  15. JC

    Wow – simply stunning! I watched the Moon graze Venus this morning. The Moon appeared to lop off only one of Venus’ horns through my 20×80 binoculars from my driveway (~10 miles from NASA-JSC). My first “graze”!

  16. lhdoges

    I saw the whole thing this morning driving to work! it was spectacular!

    first I caught Venus right as it disappeared behind the moon. I thought I would miss it popping out the other side because of the dawn. But just as I nearer work (Edwards AFB), there it was!

    magnificent!

  17. Richard Smith

    I had the wonderful privilege to view this event from my second floor bedroom window over the eastern foothills in Reno Nv. The crescent upon crescent low power views of ingress and egress were absolutely incredible! I was able to view this dazzling pair in the dawn light for 45 minutes after egress. Simply stunning! Even my wife was impressed!

    What a way to start the day!

  18. Roberta

    I was in Pontotoc, MS, on the graze line. I had to leave my telescope and go to work at about 7:25 (25 minutes before the moon crossed Venus’ path). But I was able to find a spot to watch it naked eye, and even in broad daylight I could see the faint crescent moon and Venus grow noticably dimmer as it passed beneath it. It definately made my top 10 list!

  19. Roberta

    I was in Pontotoc, MS, on the graze line. I had to leave my telescope and go to work at about 7:25 (25 minutes before the moon crossed Venus’ path). But I was able to find a spot to watch it naked eye, and even in broad daylight I could see the faint crescent moon and Venus grow noticably dimmer as it passed beneath it. It definately made my top 10 list!

Comments are closed.