Great Weekend for Viewing the Night Sky
This is a fabulous weekend for getting out and taking a look at the night sky as two extraordinary things are happening. Venus and the Moon will be very close together in the west just after sunset, and the International Space Station (ISS) will make several very bright passes overhead. Depending on where you live, you may also be able to see the Space Shuttle (STS-132) as it approaches the Space Station. It’s absolutely worth getting out for a look, especially if you’re already planning to be out for a picnic, baseball game, or just walking the dog.
Be advised that details will vary somewhat from location to location. It’s easy to find out specifics for wherever you’ll be thanks to web sites like Heavens Above or NASA’s SkyWatch. I’ll describe conditions for the San Francisco Bay area (where I live) and also for Nashville, Tennessee (where I have lots of family and friends).
Venus and the Moon At Conjunction
About 20 to 30 minutes after sunset on Saturday, May 15th you should begin to look just above the horizon to the west. (This time of year, and given Daylight Savings Time in the US, sunset will be around 8:15pm and twilight will end around 8:40pm.) The moon will be a very thin crescent and Venus will shine brightly just above it and to the left. It won’t be dark until after 9pm but if you don’t have a clear view of the western horizon you may lose sight of the Moon and Venus before then. Watch for as long as you can, as the darker it gets the more of the unlit portion of the Moon you’ll be able to see.
On Sunday night, May 16th the Moon and Venus will be also very close together, but the Moon’s position will have moved so that Venus is closer to the horizon and the Moon is to its upper left, nearly an exact reversal in position and spacing from Saturday night. The two objects will, therefore, be higher in the sky and you’ll have more time to enjoy seeing them before they disappear below your western horizon. Also, the crescent of the Moon will be twice as thick on Sunday as on Saturday. (About 10% of the Moon’s surface will be illuminated on Sunday compared to about 5% on Saturday. This means the Moon will be twice as bright on Sunday too.)
I use Stellarium, a free open source planetarium program, to view the night sky and plan my observing sessions, and it here’s its view of Venus and the Moon looking slightly northwest from my back yard on Saturday evening, May 15th:
The International Space Station
By astonishing coincidence on Saturday and Sunday evening, just as the Sun goes down and the Moon and Venus drift together low in the west, the International Space Station will pass west to east and shine very brightly over head - almost as bright as Venus. I’ve seen ISS pass overhead several times in the last few months and believe me when I tell you it’s startlingly bright and mesmerizing when you realize it’s a man-made craft, with people on board, passing approximately 200 miles overhead.
It’s important to note that for some US cities (generally those in the western US) the bright pass will be on Saturday night and for others(generally those in the eastern US) it the bright pass will be on Sunday night. Exactly when it will appear, how long it will be visible, and how high in the sky it will go varies greatly so you’ll want to consult Heaven’s Above or NASA’s SkyWatch to be sure.
For the San Francisco Bay Area ISS will make a bright pass overhead starting at 9:35pm Pacific Time on Saturday night, May 15th. It will appear on the horizon in the northwest, pass very close to the Moon and Venus, and continue rising as it speeds eastward. Watch closely and you’ll see ISS pass close to the planets Mars and Saturn before it disappears out of sight in the Earth’s shadow just a few seconds after 9:41pm. The entire visible pass lasts about five and a half minutes so you’ll have plenty of time to enjoy it. Here’s the detailed path as calculated by Heavens Above:
Path of ISS over the San Francisco Bay Area — Saturday, May 15th. (From Heavens Above)
For Nashville, Tennessee the bright overhead pass of ISS is on Sunday, May 16th. Interestingly the path taken is almost exactly the same as the above chart. ISS appears low in the northwest at 8:55pm Central Time, moves past Mars and Saturn, and disappears into Earth’s shadow at 9:02pm Central Time.
Special Guest - The Space Shuttle
If you can see ISS on either Saturday or Sunday there’s a good chance you can spot Space Shuttle Atlantis too. It lifted off from Kennedy Space Center on Friday, May 14th as the last scheduled Space Shuttle mission ever (STS-132) and will be spending the weekend catching up with ISS prior to docking late on Sunday. Consult Heavens Above or NASA SkyWatch for specifics.
Good Luck - I Hope You Have Clear Skies!
I’m planning to be outside both Saturday and Sunday evenings enjoying the view of the Moon and Venus, watching for ISS, and hoping for one last glimpse of the Space Shuttle before it retires.
