This Week's Sky at a Glance, April 14 – 23

FRIDAY, APRIL 14

■ Venus is still between Aldebaran and the Pleiades, as shown below. Watch the Pleiades sink farther down away from Venus day by day. This evening they're 5° apart. They'll widen by 1° per day, to 12° apart a week from now.

■ Meanwhile, Mars this evening shines just a small fraction of a degree from Epsilon Geminorum, one fifth as bright. Binoculars give a fine view. See "This Week's Planet Roundup" below.

SATURDAY, APRIL 15

■ In early dawn Sunday morning, spot the waning crescent Moon very low in the east-southeast. About 5° above it is distant Saturn, magnitude 1.0, beginning its nearly year-long apparition.

SUNDAY, APRIL 16

■ Right after dark, the Sickle of Leo stands vertical high in the south. Its bottom star is Regulus, Leo's brightest. Leo himself is walking horizontally westward. The Sickle forms his front leg, chest, mane, and part of his head. Off to the left, a long right triangle forms his hind end and long tail.

■ The Lion and the Mouse. A few degrees west of the top of Leo's Sickle are Kappa and Lambda Leonis, magnitudes 4.5 and 4.3, separated by 3½°. They form the nose and chin of the Lion's stick figure. Due south of Lambda (the chin) by ½° is the galaxy NGC 2903. It's 9th or 10th magnitude visually, making it Leo's second-brightest galaxy. In his April Binocular Highlight column, Matt Wedel admits that this is not a binocular object except for large binocs under a dark black sky. But my 6-inch reflector at 95x can reveal it even through suburban light pollution, as a faint gray wisp. It's elongated almost north-south. "There's nothing else nearby," Matt writes in the April Sky & Telescope, "giving the galaxy the lonely aspect of a mouse before the mighty celestial lion."

MONDAY, APRIL 17

■ After dark, look high in the west for Pollux and Castor lined up almost horizontally (depending on your latitude). Mars, looking similar, is a third dot below them.

Pollux and Castor form the top of the enormous Arch of Spring. To their lower left is Procyon, the left end of the Arch. Farther to their lower right is the other end, formed by Menkalinan (Beta Aurigae) and then brilliant Capella. Venus shines under its Arch's right side. The whole thing sinks in the west through the evening.

Modern skywatchers are not alone in seeing the Arch of Spring as one big asterism. Extend it down past Procyon to add Sirius, and you've got the Hawai‘ian Canoe-Bailer of Makali‘i. Looks big enough to bail the whole ocean.

TUESDAY, APRIL 18

■ Right after dark, Orion is getting ever lower in the southwest in his spring orientation: striding down toward the right with his belt horizontal. His belt points left toward Sirius and right toward Aldebaran and, farther on, Venus.

WEDNESDAY, APRIL 19

■ Arcturus shines brightly in the east these evenings. The Big Dipper, high in the northeast, points its curving handle down to the lower right toward it.

Arcturus forms the pointy end of a long, narrow kite asterism formed by the brightest stars of Boötes, the Cowherd. The kite is currently lying on its side to Arcturus's left. The head of the kite, at the far left, is bent slightly upward. The kite is 23° long, about two fist-widths at arm's length.

■ Now turn northwest. The brightest star there is Capella, Arcturus's near-equal. They stand at exactly the same height above your horizon around the very end of twilight, depending on your latitude.

■ New Moon (exactly so at 12:35 a.m. tonight Eastern Daylight Time).

THURSDAY, APRIL 20

■ Catch your record-young Moon? The Moon is less than a day old as seen shortly after sunset from North America. Starting about 15 minutes after sunset, use binoculars or a telescope to see if you can detect it just above the west-northwest horizon. If you do, can you then see any trace of it with the naked eye? For East Coast observers the Moon will be only 19 or 20 hours old; for the West Coast, 23 hours old. That's very nearly the youngest Moon that's theoretically possible to see. If you succeed note the time, and find the Moon's exact age since it was new 12:35 a.m. on this date Eastern Daylight Time.

If you manage to sweep up faint little Mercury, magnitude 2.0 now, look for the Moon-shred below it by 6°.

The short bit of a crescent, if you succeed, will be nowhere near as clear, long, and unbroken as in the March 20th illustration below. Long-lens photography (use a tripod) and some careful image processing may pull it out of the bright haze better that you eye can. It'll be oriented like a shallow cup. See the April Sky & Telescope, page 50. Good luck.

FRIDAY, APRIL 21

■ Look for the thin crescent Moon, much easier now, far lower right of Venus in twilight as shown below. As the sky gets darker watch for Aldebaran to appear, and then, much fainter, the Pleiades.

SATURDAY, APRIL 22

■ Venus, the crescent Moon, and Aldebaran form a nearly isosceles triangle in the west as darkness falls, as shown above. The long sides of the triangle are both 8° long (for much of the Americas).

SUNDAY, APRIL 23

■ Now the thickening Moon shines over Venus during and after dusk, as shown above.

 

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This Week's Planet Roundup

Mercury is fading fast in the western twilight: from a modest magnitude +0.6 on Friday April 14th to an invisible (in the low twilight) +2.3 a week later. Early this week, use binoculars to help hunt for Mercury about two fists at arm's length to the lower right of Venus.

Venus (magnitude –4.1, in Taurus) is the brilliant "Evening Star" in the west during and after dusk. It doesn't set until two hours after full darkness. In a telescope Venus is a dazzling little gibbous globe (72% sunlit) 15 or 16 arcseconds in diameter. It's gradually enlarging and waning in phase. It'll be 50% lit by late May and a dramatic crescent from mid-June through mid-July.

Mars is crossing Gemini. Look for it high in the west in early evening, lower in the west later. It's upper left of Venus by three or four fists at arm's length, and below Pollux and Castor.

Mars has faded to magnitude +1.2, the same brightness as modest Pollux above it. But Mars shows a deeper orange tint.

Mars is nearly on the far side of its orbit from us, so in a telescope it's just a tiny blob 5½ arcseconds wide.

Jupiter is out of sight in conjunction with the Sun.

Saturn, magnitude +1.0 in dim Aquarius, is emerging into early-dawn view low in the east-southeast. Binoculars help. The thin waning Moon hangs under it on the 16th.

Faint Uranus and Neptune are out of sight, very low in the evening and morning twilight respectively.

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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 and graphics that also depend on longitude (mainly Moon positions) are for North America.

Eastern Daylight Time (EDT) is Universal Time minus 4 hours. UT is sometimes called UTC, GMT, or Z time.

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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 a more detailed constellation guide covering the whole evening sky, use the big monthly map in the center of each issue of Sky & Telescope, the essential magazine of astronomy.

Once you get a telescope, to put it to good use you'll need a much more 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 all 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) or Uranometria 2000.0 (stars to magnitude 9.75). And be sure to read How to Use a Star Chart with a Telescope. It applies just as much to charts on your phone or tablet as to charts on paper.

You'll also want a good deep-sky guidebook. A beloved old classic is the three-volume Burnham's Celestial Handbook. An impressive more modern one is the big Night Sky Observer's Guide set (2+ volumes) by Kepple and Sanner.

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. 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."

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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.

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"The dangers of not thinking clearly are much greater now than ever before. It's not that there's something new in our way of thinking, it's that credulous and confused thinking can be much more lethal in ways it was never before."
            — Carl Sagan, 1996

"Facts are stubborn things."
            — John Adams, 1770

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