This Week's Sky at a Glance for October 8 – 16

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This Week's Sky at a Glance
Some daily events in the changing sky for October 8 – 16
by Alan M. MacRobert
Periodic Comet Hartley 2 is at its best early this week —before moonlight becomes a problem later in the week. At 6th magnitudethe comet is visible in binoculars in a moderately dark sky, well placedin the evening high in Perseus. It has a small central condensation anda large, dim coma. As a result of this, what you'll see of it dependsstrongly on the quality of your sky; in the last few days differentobservers have reported the comet as anywhere from magnitude 5.3 to 7.2overall. Use the finder chart below, and see ourarticle.
Thisweek Comet Hartley 2 speeds across Perseus toward bright Capella. Clickimage for larger chart. The comet symbols (visibility much exaggerated)are placed at 0:00 UT on the October dates indicated. Remember, 0:00 UTfalls on the evening of the previous date in the times zones of the Americas.
Sky & Telescope
Nowat naked-eye visibility, Mira in Cetus climbs the eastern sky in lateevening — in this case, over hills in Iran. Click image for larger view.
Copyright Babak Tafreshi (
Friday, October 8 Mira, the brightest long-periodred variable star, is having an unusually bright maximum! As of October7th many observers were reporting it at magnitude 3.1, very plainlyvisible to the naked eye. Will it grow any brighter? It's up in goodview in the east-southeast by 10 or 11 p.m. daylight saving time. Seethe comparison-star chart in the SeptemberSky & Telescope, page 58.
It's certainly fall now; look for Arcturus, the brightest star ofBootes, low in the west-northwest as twilight fades. To its right in thenorth-northwest, the Big Dipper is lying almost sideways now andholding water.
Comet Hartley 2 is still only about 1° from the Perseus Double Cluster this evening. Think photo opportunity!
Use binoculars to look for these objects hiding in bright twilight shortly after sunset.
Sky & Telescope diagram
Saturday, October 9
Soon after sunset, usebinoculars to look for the thin Moon and Venus very low in thesouthwest, as shown here. Can you also find Mars and Antares?
Late tonight (for North America) Comet Hartley 2 grazes Eta Persei,magnitude 3.8, the tip of Perseus's hat. Eta Per is a pale-yellow-orangeK3 giant, which, in a telescope, should make a nice color contrast with the comet's pale green.
Jupiter's Great Red Spot should cross Jupiter's central meridian (theimaginary line down the center of the planet's disk from pole to pole)around 1:20 a.m. Sunday morning EDT; 10:20 p.m. Saturday evening PDT.The "red" spot appears very pale orange-tan. It should be visible forabout an hour before and after in a good 4-inch telescope if theatmospheric seeing is sharp and steady. A light blue or green filterhelps. For all of the Red Spot's central-meridian crossing times, goodworldwide, use ourRed Spot calculator or print out ourlist for the rest of this observing season.
Thewaxing Moon, on its way back into the evening sky, passes Antares onits way out. (These scenes are drawn for the middle of North America.European observers: move each Moon symbol a quarter of the way towardthe one for the previous date. For clarity, the Moon is shown threetimes actual size.)
Sky & Telescope diagram
Sunday, October 10
In twilight, look for twinkly littleAntares upper left of the crescent Moon low in the southwest, as shownhere. Binoculars help.
Jupiter's Red Spot should transit around 9:12 p.m. EDT.
Monday, October 11
Look for Antares lower right of the Moon after sunset this evening, as shown here.
Jupiter's Red Spot should transit around 2:58 a.m. Tuesday morning EDT; 11:58 p.m. Monday evening PDT.
Tuesday, October 12
Do you know littleSagitta's lone Messier object? Find the loose globular cluster M71 rightin the Arrow's shaft using Gary Seronik's Binocular Highlight articleand chart in the OctoberSky & Telescope, page 45. Sagitta is also your jumping-off point for brighter M27 right nearby.
Jupiter's Red Spot should transit around 10:50 p.m. EDT.
Wednesday, October 13
Right after dark, look for the Sagittarius Teapot tipping directly below the Moon.
Thursday, October 14
First-quarter Moon (exact at 5:27 p.m. EDT). As the stars come out, look high above the Moon for Altair.
Jupiter's Red Spot should transit around 12:28 a.m. Friday morning EDT; 9:28 p.m. Thursday evening PDT.
Friday, October 15
Look just upper right ofthe Moon this evening (as seen from most of North America) for the3rd-magnitude stars Beta and Alpha Capricorni, in that order countingup. Alpha is a double star that, with good or well-corrected vision, youcan just resolve with the unaided eye. Binoculars resolve it easilyinto a golden-yellow pair.
Saturday, October 16
Jupiter's Red Spot should transit around 8:19 p.m. EDT.