Friday, April 3
■ Venus this evening shines in the upper left edge of the Pleiades, as shown above. How soon before the end of twilight can you first begin to see the little cluster? Bring your telescope, binoculars, and/or long-focus camera! This is a once-in-eight-years event. For more see Bob King's The Pleiades Welcome Venus, with photo tips.
Of course they're nowhere near each other, really. Venus this evening is 5.2 light-minutes from us, while the Pleiades are 440 light-years in the background. That's 45 million times farther away. To put this in scale-model perspective: If Venus were a shiny dust speck floating three inches in front of your eye, the Pleiades stars would be 1,200 miles behind it halfway across the continent: blue-white-hot marbles and peas, searingly brilliant, scattered in a volume of black space about 30 miles wide.
Also in and around this volume would be scores of dimmer, yellow-hot BBs and orange-hot mustard seeds, and roughly a thousand much dimmer, merely red-hot sand grains.
On average, each would be a few miles from its nearest neighbor.
Saturday, April 4
■ At this time of year, the two Dog Stars stand vertically aligned around the end of twilight. Look southwest. Sirius in Canis Major is the brightest point in the sky after Venus. Procyon in Canis Minor is above Sirius, by about two fists at arm's length.
■ Look to the right or lower right of the gibbous Moon this evening for Regulus, the leading star of Leo. They're about 5° apart for North America. Above the Moon by a similar distance or a bit more is Algieba, the second-brightest star in the Sickle of Leo after Regulus. The Sickle, a backward question mark, forms the stick-figure Lion's head, neck, chest, and front foot.
Sunday, April 5
■ Right after dark, Orion is still well up in the southwest but in his spring orientation: striding down to the right, with his belt horizontal. The belt points left toward Sirius and right toward Aldebaran and, farther on, Venus and the Pleiades.
Look at Orion's two shoulders. Orange Betelgeuse is obviously brighter than Bellatrix to its lower right, now that Betelgeuse has been steadily recovering brightness for almost two months. In early February it bottomed out at magnitude 1.6, the same as steady Bellatrix. As of March 29th Betelgeuse had doubled in brightness back to 0.9. The dust clouds in its outer atmosphere are clearing, if that's what its problem was.
Monday, April 6
■ Vega, the bright "Summer Star," rises in the northeast late these evenings. Exactly where should you watch for it to come up? Spot the Big Dipper almost overhead in the northeast. Look at Mizar at the bend of its handle. If you can see Mizar's tiny, close companion Alcor (binoculars show it easily), follow a straight line from Mizar through Alcor all the way down to the horizon. That's where Vega will be when it makes its appearance.
Tuesday, April 7
■ Full Moon (exactly so at 10:35 p.m. EDT). This is a "supermoon," meaning it appears just a trace larger than average; the Moon was at perigee less than a day ago.
The Moon shines in central Virgo. Look for bright Arcturus two or three fists at arm's length to its left, and Spica much closer below the Moon or to its lower right.
Wednesday, April 8
■ High above the Big Dipper late these evenings, nearly crossing the zenith, are three pairs of dim naked-eye stars, all 3rd or 4th magnitude, marking the Great Bear's feet. They're also known as the Three Leaps of the Gazelle, from early Arab lore. They form a long line roughly midway between the Bowl of the Big Dipper and the Sickle of Leo; see the evening constellation chart in the center of the April Sky & Telescope.
According to the Arabian story, the gazelle was drinking at a pool — the big, dim Coma Berenices star cluster — and bounded away when alerted by a flick of Leo's nearby tail, Denebola. Leo, however, seems quite unaware; he's facing the other way.
Thursday, April 9
■ This is the time of year when, as the last of twilight fades away, the bowl of the dim Little Dipper extends straight to the right of Polaris. High above the end-stars of the Little Dipper's bowl, you'll find the end-stars of the Big Dipper's bowl.
Friday, April 10
■ The asteroid 3 Juno, just past opposition and visible in a small telescope at magnitude 9.5, is passing a mere ½° southwest of the 3rd-magnitude star Delta Virginis. You've got about two hours of dark sky this evening between the end of twilight and moonrise. Use the finder chart in the April Sky & Telescope, page 50. (The position ticks every three days there are for 0:00 UT on the dates indicated, which in North America falls on the evening of the previous date.) The chart follows Juno on through the rest of the month as it fades to magnitude 10.
■ Algol and its constellation Perseus, off to the right of Venus, are sinking ever lower in the northwest after dark as the season advances. For skywatchers in western North America, Algol goes through one of its eclipses this evening. It should be at its minimum brightness, magnitude 3.4 instead of its usual 2.1, for a couple hours centered on 9:14 p.m. Pacific Daylight Time.
Saturday, April 11
■ Right after dark, look southwest and find Procyon high above brilliant Sirius. Look upper left of Procyon by 15° (about a fist and a half at arm's length) for the dim head of Hydra, the enormous Sea Serpent. His head is a group of 3rd- and 4th-magnitude stars about the size of your thumb at arm's length.
About a fist and a half lower left of Hydra's head shines Alphard, his 2nd-magnitude orange heart. The rest of Hydra zigzags (faintly) from Alphard all the way down to the southeast horizon.
This Week's Planet Roundup
Mercury is buried in the glow of sunrise.
Venus (magnitude –4.6, in Taurus near the Pleiades) is the dazzling white "Evening Star" high in the west during and after dusk. Venus doesn't set in the west-northwest until a good 2½ hours after complete dark.
On April 3rd Venus shines in the edge of the Pleiades, then on subsequent evenings it blazes above the cluster. Their separation widens by about 1° per day.
In a telescope, Venus is slightly less than half lit and 27 arcseconds in diameter. It will continue to enlarge in size and wane in phase to become a dramatically thin crescent in late May.
Mars, Jupiter, and Saturn (magnitudes, +0.7, – 2.2, and +0.7, respectively) are grouped low in the southeast as dawn begins, as shown below. Jupiter is by far the brightest. Left of it is yellowish Saturn, and left of Saturn is orange Mars. Each morning Mars moves visibly farther from Saturn.
Uranus is disappearing into the western evening twilight.
Neptune is hidden in the glow of sunrise.
All descriptions that relate to your horizon — 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) is Universal Time (UT, UTC, GMT, or Z time) minus 4 hours.
Want to become a better astronomer? Learn your way around the constellations. They're the key to locating everything fainter and deeper to hunt with binoculars or a telescope.
This is an outdoor nature hobby. For an easy-to-use constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential guide to astronomy.
Once you get a telescope, to put it to good use you'll need a detailed, large-scale sky atlas (set of charts). The basic standard is the Pocket Sky Atlas (in either the original or Jumbo Edition), which shows stars to magnitude 7.6.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many. The next up, once you know your way around, are the even larger Interstellarum atlas (stars to magnitude 9.5) and Uranometria 2000.0 (stars to magnitude 9.75). And read how to use sky charts with a telescope.
Can a computerized telescope replace charts? Not for beginners, I don't think, and not on mounts and tripods that are less than top-quality mechanically (meaning heavy and expensive). And as Terence Dickinson and Alan Dyer say in their Backyard Astronomer's Guide, "A full appreciation of the universe cannot come without developing the skills to find things in the sky and understanding how the sky works. This knowledge comes only by spending time under the stars with star maps in hand."
Audio sky tour. Out under the evening sky with your earbuds in place, listen to Kelly Beatty's monthly podcast tour of the heavens above. It's free.