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Celestial Trifecta on Monday, Dec. 7

Monday, December 7, has three celestial highlights for observers in the South Bend, IN, region--a comet, an occultation, and satellite passes.


Before sunrise in the eastern twilight, find a triangle formed by the crescent moon, Venus, and Comet Catalina, with the faint comet requiring a telescope or binoculars. See Comet Catalina in the Morning Sky.


The moon occults

Venus in the daytime sky. Venus appears to glide into the crescent around 12:20 p.m. and reappears from behind the dark side of the round moon around 1:34 p.m. See Occult Skygazing at Fiddler's Hearth for an observing opportunity in South Bend.


After the sun sets around 5:15 p.m., satellites offer a double-header. First, around 6:16 p.m., an Iridium satellite zooming over Michiana "flares" as it reflects sunlight.

The satellite is moving north to south, and it brightness rapidly when it's low in the southern sky near Capricorn, as shown in the star chart.

[Actually, for South Bend residents, a brighter flare occurs exactly 24 hours earlier in the same spot, 30 degrees above the horizon at 188 degrees of azimuth (compass bearing). The Dec. 7 flare is centered over Elkhart and Goshen (see map), but the Sunday, Dec. 6, flare occurs after the satellite passes directly over South Bend.]

For more satellite predictions, see Heavens-Above.

But, wait, there's more. At 7:00 p.m., the International Space Station (ISS) rises above the western horizon, passes the bright star Vega in the Summer Triangle asterism, passes South Bend's birthday star Eltanin, and heads toward Polaris before dimming in the shadow of the earth around 7:05 p.m.. The path of ISS below is adapted from the more accurate starfield of Heavens Above, shown further below.

The ground track shows the path of ISS and its appearance from 7:00 to 7:05 p.m. EST on Dec. 7, 2015.

Most of the mentioned celestial highlights require a low, unobstructed horizon, so plan in advance the site from which you will observe.

If you've read this far, I'll tell you that a higher ISS pass will occur Saturday, Dec. 5. The space station rises out of the southwest after 7:07 p.m., and heads to 70 degrees of altitude before it fades into the earth's shadow at 7:11 p.m. Note that when ISS disappears, its visible streak ends near Indiana's Bicentennial Star named Scheat.

As if that isn't enough, December 8, just after 6:06 p.m., the ISS makes its best pass yet, zooming from southwest to high overhead (74 degrees) to northeast. It'll be obvious when it's high until it disappears low in the northeast at 6:12 p.m..


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