Author Archives: Alan MacRobert

About Alan MacRobert

Sky & Telescope senior editor Alan MacRobert has been covering all aspects of astronomy since 1982.

This Week's Sky at a Glance

This Week’s Sky at a Glance, December 19 – 27

Some daily sky sights among the ever-changing Moon, planets, and stars. Friday, December 19 Have you ever tried to catch Sirius actually rising? If you can find a good view down to the east-southeast horizon, watch for Sirius emerging about two fists at arm's length below Orion's Belt. It now rises sometime around 7:30...

Comet-2014Q2_Rhemann_Nov-27-2014_489x274

Binocular Comet Lovejoy Heading Our Way

A new Comet Lovejoy, C/2014 Q2, is heading our way. It may brighten to 5th magnitude from late December through much of January as it climbs into excellent viewing position for the Northern Hemisphere, high in the dark winter sky.

This Week's Sky at a Glance

This Week’s Sky at a Glance, December 12 – 20

Some daily sky sights among the ever-changing Moon, planets, and stars. Friday, December 12 This is the time of year when, around 8 or 9 p.m., Cassiopeia stands very high in the north as a flattened letter M. When will you see it perfectly level? This mostly depends on how far east or west...

This Week's Sky at a Glance

This Week’s Sky at a Glance, December 5 – 13

Some daily sky sights among the ever-changing Moon, planets, and stars. Friday, December 5 The Moon is essentially full this evening and Saturday evening both (it's exactly full at 7:27 a.m. Saturday morning EST.) On Friday evening in the Americas, look for Aldebaran less than about 2° from the Moon. Watch the Moon shift...

This Week's Sky at a Glance

This Week’s Sky at a Glance, Nov. 28 – Dec. 6

Some daily sky sights among the ever-changing Moon, planets, and stars. Friday, November 28 First-quarter Moon (exactly first-quarter at 5:06 a.m. Saturday morning EST). Look this evening for Fomalhaut far to the Moon's lower left, and for Enif, the nose of Pegasus, almost as far to the Moon's upper right. Saturday, November 29 The...

This Week's Sky at a Glance

This Week’s Sky at a Glance, November 14 – 22

Some daily sky sights among the ever-changing Moon, planets, and stars. Friday, November 14 Keep an eye on little Mars in the southwest at dusk. It will keep hanging in there month after month through this winter, as constellations of the zodiac slide behind it. Last-quarter Moon (exact at 10:16 a.m. EST). The Moon...

This Week's Sky at a Glance

This Week’s Sky at a Glance, November 7 – 15

Some daily sky sights among the ever-changing stars and planets. Friday, November 7 The Moon, just past full, rises in the east at dusk. Once it climbs high, look for orange Aldebaran to its lower left and the Pleiades to its upper left. Catch Mercury in Saturday's dawn, as shown here. Saturday, November 8...

This Week's Sky at a Glance

This Week’s Sky at a Glance, October 24 – November 1

Some daily sky sights among the ever-changing stars and planets The monster sunspot continues in view; see "This Week's Planet Roundup" below. Friday, October 24 As the stars come out, Deneb is nearly straight overhead for skywatchers at mid-northern latitudes. Brighter Vega is west of the zenith. Altair is farther from the zenith toward...

This Week's Sky at a Glance

This Week’s Sky at a Glance, October 17 – 25

Some daily sky sights among the ever-changing stars and planets Monster sunspot alert — see "This Week's Planet Roundup" below. Friday, October 17 Before dawn Saturday morning, Jupiter shines above the waning Moon, as shown at right. Although they look rather close together, Jupiter is 2,100 times farther in the background — it's at...

This Week's Sky at a Glance

This Week’s Sky at a Glance, October 3 – 11

Some daily celestial sights among the ever-changing stars and planets Friday, October 3 As evening twilight fades away, look very far to the lower left of the Moon for Fomalhaut, the Autumn Star, already climbing up from the southeast horizon. Saturday, October 4 The W pattern of Cassiopeia stands vertically (on its dimmer end)...

Mutual Events of Jupiter’s Satellites in 2014–15

A full season of mutual events for Jupiter's four largest satellites As Jupiter shines brightly down from the sky during its 2014–15 apparition, quite often Jupiter's four big Galilean moons will occult and cast their shadows on each other. A "mutual events season" like this happens about every 6 years, when Earth and Sun...

Planck temperature map of universe

What’s Next for Inflation Cosmology – New Updates

Our July 2014 cover story was the apparent discovery of gravitational waves from the instant of inflation when the Big Bang took shape. Just as the article was printed, a serious challenge to the discovery appeared: the researchers had underestimated the amount of interstellar dust that could be contaminating their data. Here are more...

This Week's Sky at a Glance

This Week’s Sky at a Glance, September 5 – 13

Friday, September 5 Saturn, Mars, Delta (δ) Scorpii, and Antares form an equally-spaced ragged line in the southwest at dusk, as shown at right. Delta Scorpii used to be a bit dimmer than Beta above it. Then in July 2000 it doubled in brightness. It has remained bright, with slow fluctuations, ever since. Look...

This Week's Sky at a Glance

This Week’s Sky at a Glance, August 22 – 30

Friday, August 22 Altair is the brightest star shining halfway up the southeastern sky after nightfall. Look to its left, by a little more than a fist at arm's length, for the dim but distinctive constellation Delphinus, the Dolphin. He's leaping leftward, just below the Milky Way. In Saturday's dawn, the thin waning crescent...

This Week's Sky at a Glance

This Week’s Sky at a Glance, August 8 – 16;

Friday, August 8 Already you may see an occasional Perseid meteor if you keep an eye on the night sky. The shower's peak night is predicted for next Tuesday (August 12–13), but moonlight will compromise the view all week. Look northeast as the stars come out for W-shaped Cassiopeia. It's still not quite as...

This Week's Sky at a Glance

This Week’s Sky at a Glance, August 1 – 9

Friday, August 1 At dusk this evening, the Moon forms the lower-right end of a very long, curving line of celestial objects. Counting to the Moon's upper left, these are Spica, Mars, and Saturn, as shown here. Today is Lammas Day or Lughnasadh, one of the four traditional "cross-quarter" days midway between the solstices...