贵州省大方县图片:This Week's Sky at a Glance for April 22 –30

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This Week's Sky at a Glance

Some daily events in the changing sky for April 22 –30

by Alan M. MacRobert

T Pyxidis in outburst on April 15th, the day after its discovery. North is up. See before-and-after animation (with south up).Ernesto Guido & Giovanni SosteroThe recurrent nova T Pyxidis erupted last week for the first timesince December 1966. It's now magnitude 7.5 (as of April 22nd) and islikely to brighten to about 6.4 by May 20th. It's visible right afterdark from mid-northern latitudes and points south. See our article T Pyxidis Finally Blows Again.

Friday, April 22

  • The Lyrid meteor shower shouldpeak late tonight, but it's usually quite weak. The best chance to seean occasional Lyrid will be around midnight daylight-saving time, whenLyra is up fairly high but the Moon hasn't yet risen.
  • Justsouth of Regulus is the dim but galaxy-riddled constellation Sextans,the Sextant. Dig up some of its far sights using Sue French's Deep-SkyWonders column, chart, and images in the April Sky & Telescope, page 58.

    Saturday, April 23

  • Capella is the brighteststar shining in the northwest right after dusk. Arcturus is thebrightest in the east. Both are magnitude zero — and this week, bothstand at exactly the same height above your horizon around nightfall(depending on your latitude). How accurately can you time this event foryour location?

    Sunday, April 24

  • Last-quarter Moon (exactat 10:47 p.m. EDT). The Moon, in Capricornus, rises long after midnighttonight (daylight-saving time) and stands nearly in the south at Mondaysunrise.

    Monday, April 25

  • In late twilight, have youbeen keeping an eye on bright Sirius in the southwest and Orion in thewest? They're still in view but sinking lower daily. How much later inthe season can you keep them in sight?

    Tuesday, April 26

  • Sirius, the Dog Star,still twinkles low in the southwest right after dusk. High above it isProcyon, the Little Dog Star. Very far to Procyon's upper left isRegulus in Leo. Nearly halfway from Procyon to Regulus, look for a dimbut distinctive asterism: the head of Hydra, the Sea Serpent. It's aboutthe size of the end of your thumb at arm's length.

    Wednesday, April 27

  • At the end of twilightthis week, look for the Big Dipper tilting over very high in thenortheast — almost overhead, depending on your latitude. This is alsothe time of year when, right after nightfall, the Little Dipper extendshorizontally to the right from Polaris.

    Beforesunrise as April ends, the waning crescent Moon guides the way to fourplanets on the down-low. One should be easy to spot; the other three area real challenge. (The visibility of the fainter objects in brighttwilight is exaggerated here. These scenes are drawn for the middle ofNorth America. European observers: move each Moon symbol a quarter ofthe way toward the one for the previous date.)Sky & Telescope diagramThursday, April 28

  • A dawn challenge: Set the alarm to get up Friday morning well before your local sunrise time,grab binoculars or telescope, and get to a spot with a view of theeastern horizon by a half hour before sunrise. The waning crescent Moonwill be hanging in the east. If the air is clear Venus should be easy topick up far to its lower left. Try next for Mercury, Jupiter, and, for areal challenge, tiny Mars next to Jupiter, as shown here.

    Friday, April 29

  • Was it cloudy this morningat dawn? Set your alarm to try again Saturday morning for the Moon,Venus, Mercury, Jupiter, and Mars. This time the Moon is thinner andcloser above Venus, as shown here.
  • Late tonight thelarge, 10.3-magnitude asteroid 7 Iris will occult (cover) an identicallybright star in Cancer for up to 13 seconds as seen from a track runningfrom northern Washington State through Iowa and Illinois to Virginiaand North Carolina. Maps, finder charts, and full information.

    Saturday, April 30

  • The big Coma BerenicesStar Cluster is often hidden by light pollution. But if you get to adark sky, be sure to look for it — a very large, dim glow a third of theway from Denebola (the tail star of Leo) to the end of the Big Dipper'shandle.

    • This Week's Sky at a Glance for April 22 –30 This Week's Sky at a Glance for March 25 – April 2. This Week's Sky at a Glance for April 8 – 16 This Week's Sky at a Glance for April 15 – 23 This Week's Sky at a Glance for January 14 – 22 This Week's Sky at a Glance April 1 – 9 This Week's Sky at a Glance for December 31 – January 8 This Week's Sky at a Glance for January 7 – 15. This Week's Sky at a Glance for January 21 – 29 This Week's Sky at a Glance for January 28 – February 5 This Week's Sky at a Glance for February 4 – 12 This Week's Sky at a Glance for February 18 – 26. This Week's Sky at a Glance for March 4 – 12 This Week's Sky at a Glance for March 18 – 26 This Week's Sky at a Glance for May 20 – 28 This Week's Sky at a Glance for May 27 – June 4. This Week's Sky at a Glance for June 3 – 6 This Week's Sky at a Glance for June 17 – 25 This Week's Sky at a Glance for July 29 – August 6 This Week's Sky at a Glance for September 8 – 17 This Week's Sky at a Glance for September 16 – 24 This Week's Sky at a Glance for June 24 - July 2 This Week's Sky at a Glance - SkyandTelescope.com This Week's Sky at a Glance February 25 – March 5.