This Week's Sky at a Glance for September 9 – 18

来源:百度文库 编辑:神马文学网 时间:2024/03/28 23:12:52
This Week's Sky at a Glance
Some daily events in the changing sky for September 9 – 18
by Alan M. MacRobert
Thursday, Sept. 9
Mira, the prototype red long-period variable star in Cetus, is on its way to a maximum predicted for early October. It's probably not quite visible to the unaided eye yet but should be easy in binoculars. You'll need to look for it after about midnight, however. See the chart in the SeptemberSky & Telescope, page 58.
 
Soon after sunset on September 10th and 11th, Venus and the crescent Moon guide the way to some much more difficult sights. The visibility of faint objects in bright twilight is exaggerated here; bring binoculars. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date. In the Far East, move it halfway.)
Sky & Telescope diagram
 
Friday, Sept. 10
 
Can you spot the thin Moon lower right of Venus after sunset, as shown above? In the illustration, the visibility of objects in bright twilight is exaggerated; binoculars will help.
 
 
Algol in Perseus is well up in the northeast by about 10 p.m. daylight saving time. Tonight it should be in one of its periodic dimmings, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 11:58 p.m. EDT (8:58 p.m. PDT). It takes several additional hours to fade and to rebrighten. Use ourcomparison-star chart. For all the times of Algol's minima in September and October, good worldwide, see the OctoberSky & Telescope, page 59.
 
Saturday, Sept. 11
 
Venus shines 6° or 7° to the right of the waxing crescent Moon low in the west-southwest during twilight, as shown above.
 
 
Jupiter's Great Red Spot should cross Jupiter's central meridian (the imaginary line down the center of the planet's disk from pole to pole) around 10:20 p.m. Eastern Daylight Time. It should be visible for about an hour before and after in a good 4-inch telescope if the atmospheric seeing is sharp and steady. A light blue or green filter helps. For all of the Red Spot's central-meridian crossing times, good worldwide, use ourRed Spot calculator or ourcomplete list for the rest of this observing season.
 
Sunday, Sept. 12
 
Jupiter's moon Europa slips into eclipse by Jupiter's shadow, barely off the planet's western limb, around 12:24 a.m. Monday morning EDT.
 
As the waxing Moon moves upper leftward from evening to evening, it passes Scorpius sinking for the season toward the lower right. (These scenes are drawn for the middle of North America. European observers: move each Moon symbol a quarter of the way toward the one for the previous date.)
Sky & Telescope diagram
Monday, Sept. 13
 
 
At dusk, look for Antares sparkling 3° or 4° left of the Moon, as shown here.
 
 
Jupiter's Great Red Spot should transit around 11:58 p.m. EDT.
 
Tuesday, Sept. 14
 
First-quarter Moon tonight (exact at 1:50 a.m. Wednesday morning EDT).
 
Wednesday, Sept. 15
 
Jupiter's Great Red Spot should transit around 1:36 a.m. Thursday morning EDT (10:36 p.m. Wednesday evening PDT).
 
Thursday, Sept. 16
 
The Moon shines above the handle of the Sagittarius Teapot this evening.
 
 
Jupiter's Great Red Spot should transit around 9:27 p.m. EDT.
 
Friday, Sept. 17
 
Uranus is passing 0.8° north of Jupiter tonight and tomorrow night. Although Uranus is easily visible in binoculars at magnitude 5.7, Jupiter outshines it by nearly 3,000 times at magnitude –2.9. In fact, Uranus appears roughly as bright as one of Jupiter's four Galilean moons.
 
Saturday, Sept. 18
 
You know summer is near its end: as the stars come out, Cassiopeia in the northeast is already as high as Big Dipper in the northwest!
 
 
Jupiter's Great Red Spot should transit around 11:05 p.m. EDT.
This Week's Planet Roundup
 
On what date can you first see Mercury emerging in the dawn?
Sky & Telescope diagram
Mercury is emerging from deep in the glow of sunrise and brightening rapidly. It should be clearly visible after about the 15th; look for it low due east about 45 to 30 minutes beforeyour time of sunrise. Don't confuse Mercury with little Regulus twinkling above it!
 
Venus, though bright at magnitude –4.7, is quite low in the southwest during bright evening twilight. It sets before dark.
Mars, vastly dimmer at magnitude +1.5, is 6° to Venus's upper right all week. Use binoculars. Look too for Spica (magnitude +1.0) to the lower right of Mars, as shown at the top of this page. Good luck.
Jupiter (magnitude –2.9, in Pisces) is nearing its opposition on the night of the 20th. As twilight fades, Jupiter becomes visible low in the east. It's well up in the east-southeast by mid- to late evening — by far the brightest starlike point in the sky. It's highest in the south around 1 or 2 a.m. daylight saving time.
Jupiter is having an unusually close apparition; from now through mid-October it appears 49 arcseconds wide. In fact, at opposition on the night of September 20th Jupiter will be closer than at any other time from 1963 to 2022. However, that's only 1% or 2% closer than in any year when opposition occurs from mid-August through October, including last year and next.
This is an amateur image? Taken from Earth? Star planetary imagerAnthony Wesley in Australia took this stacked-video image on August 30th at 17:38 UT, using the 14.5-inch Newtonian reflector he's pictured with at the bottom of this page. North is toward lower left.
Jupter's Oval BA, also known as Red Spot Junior, has just passed the Great Red Spot without any visible effect on either. Here, Junior is just south of (above) the Great Red Spot.
Anthony Wesley
Jupiter's Great Red Spot is near System II longitude 157°. Assuming it stays there, here's a list to print out of all theGreat Red Spot's predicted transit times for the rest of this observing season.
 
Saturn is lost in the sunset.
Uranus (magnitude 5.7) is only about 1° from Jupiter this week. They're closest (0.8°) on the 17th and 18th, with Uranus passing north of Jupiter.
Neptune (magnitude 7.8, at the Aquarius-Capricornus border) is well placed during evening. See ourfinder charts for Uranus and Neptune online or in the SeptemberSky & Telescope, page 56. Can you see any color in Uranus and/or Neptune?
Pluto (magnitude 14, in northwestern Sagittarius) is in the south-southwest after dusk, but with the moonlight this week, forget it.
P.S. regarding Pluto: We list its whereabouts because people want us to, not because "Sky & Telescope officially says Pluto is a planet!" as internet gossip would have it.
 
 
All descriptions that relate to your horizon or zenith — including the words up, down, right, and left — are written for the world's mid-northern latitudes. Descriptions that also depend on longitude (mainly Moon positions) are for North America. Eastern Daylight Time (EDT) equals Universal Time (also known as UT, UTC, or GMT) minus 4 hours.