Sky Events

(revised 11/26/11)

First, let me apologize for not keeping this page up to date. I have been revising it regularly, but in some fashion my revisions were not making to the actual Web. I think I've got that problem solved, so should be able to do better in the future.

Planets et al. Jupiter continues his solitary rule of the night sky, shining brightly high in the southeast after sundown. But the King of the Planets will start suffering some competition from Venus. The brightest planet is barely glimpsable very low in the SW as darkness falls, but by the time twilight is gone, so is Venus. She'll be slowly climbing up the western sky, night by night, and will dominate the western sky through mid-May. The two planets will be close together in mid-May.

International Space Station. The International Space Station (more info here), the largest satellite in orbit and the only permanent one continuously inhabited by human beings, is occasionally visible to the naked eye. It looks like a moving star. Its brightness varies, but it can rival the brightest planets and outshine the brightest stars when conditions are optimum. Here are the best passes coming up in the next few days, all in the early morning.

Fri., Dec. 2, 6:34-6:40 a.m. Rises in the NW; reaches maximum altitude* of 66 degrees in the NE; sets ESE. Magnitude* -3.2, brighter than any visible star or planet.

Sun., Dec. 4, 6:17-6:22 a.m. Rises WNW; peaks high (56 d) in SW; sets SE. Mag. -3.3, very slightly brighter than Friday's pass.

Mon., Dec. 5, 5:23-5:26. Appears out of Earth's shadow high (61 d altitude) in NNE (this is its maximum altitude for this pass), sets ESE. Mag. -3.2.

There are other, fainter (but still good) morning passes during this period. Morning passes come to an end Dec. 8; evening passes begin Dec. 14. For more information about the ISS, and about other satellites' appearances (including the amazing Iridium flares mentioned in South Jersey Skies for June 14), look at Heavens Above (from where the preceding information was obtained, to be honest, and you can download it yourself if you want).

* Altitude: angular distance in degrees above horizon, NOT distance in miles above Earth's surface. Straight overhead is 90 degrees, halfway up the sky is 45, the horizon is 0.

  Zenith: the point straight overhead.

  Magnitude: brightness. The brightest star in the winter sky, Sirius, has a magnitude of -1.4 (negative numbers are brighter); the brightest summer star, Vega, is at 0.0. Jupiter stands at -2.5, Venus at -4.0. The faintest star visible to someone with excellent eyesight is around +6. The Sun is -26! Magnitude estimates for the Station and Shuttle are typically underestimates: they usually appear significantly brighter than the numbers would lead you to expect. Also note: an evening pass starts out quite dim (because the Sun is shining mostly on the part of the spacecraft facing away from us). The satellite becomes brighter as it reaches its peak altitude. So have patience: don't give up too soon! Sweep your eyes along the expected path; look for a moving dot that doesn't blink. Morning passes start out a bit brighter, so are easier to pick up right away. Yes, I agree that the magnitude scale seems to be backwards: the negative numbers are brighter. That's a result of historical events; we're stuck with it.

  Weather conditions: as I tell my students, I can't be held responsible for anything that happens less than 100 miles above the Earth's surface.

Star charts, sky maps. One of the most comprehensive star charts available is at SkyMaps.com.

Questions about this page? Contact the planetarium director.

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