FRIDAY, MAY 15
■ This is the time of year when Leo the Lion starts walking downward toward the west, on his way to departing into the sunset in early summer. Right after dark, spot the brightest star fairly high in the southwest. That’s Regulus, his forefoot.
Regulus is also the bottom of the Sickle of Leo: a backward question mark extending to the right or upper right, almost a fist and a half long. It outlines the lion’s leading foot, chest, and mane.
Upper left of the Sickle, by more than a fist at arm’s length, is the long triangle marking Leo’s rear end and tail.
SATURDAY, MAY 16
■ Vega is the brightest star in the east-northeast after dark. Look 14° (about a fist and a half at arm’s length) to Vega’s upper left for Eltanin, the 2nd-magnitude nose of Draco the Dragon. Closer above and upper left of Eltanin are the three fainter stars forming the rest of Draco’s stick-figure head, also called the Lozenge. Draco always points his nose toward Vega, no matter how he’s oriented. He seems curious about it, but he has made no move on it yet.
The faintest star of Draco’s head, opposite Eltanin, is Nu Draconis. It’s a fine, equal-brightness double star for binoculars (separation 61 arcseconds, both magnitude 4.9). The pair is 99 light-years away. Both are hot, chemically peculiar type-Am stars somewhat larger, hotter, and more massive than the Sun
■ New Moon (exact at 4:01 p.m. Eastern Daylight Time).
SUNDAY, MAY 17
■ A double eclipse-emergence by Jupiter’s moons. For the eastern third of North America, Europa and Io will reappear out of eclipse by Jupiter’s shadow just three minutes apart, at 8:50 and 8:53 p.m. EDT. They will appear fairly close together about two Jupiter-widths to Jupiter’s east. For observers farther west, the sky will still be too bright.
For all the doings of Jupiter’s moons this month, good worldwide, see the May Sky & Telescope, page 51.
■ Can you see the big Coma Berenices star cluster? Does your light pollution really hide it, even on these moonless evenings? Or do you just not know exactly where to look?
It’s 2/5 of the way from Denebola, Leo’s tail tip, to the end of the Big Dipper’s handle, Ursa Major’s tail tip. Or, halfway from Denebola to Cor Caroli. Its brightest members form an inverted Y. The entire cluster is about 4° wide — a big, dim glow in a very dark sky, roughly the size of a ping-pong ball held at arm’s length. It nearly fills a binocular view. It totally overspills a telescope’s view; you don’t see anything unusual because you’re looking right through it!
Read more about this big, nearby cluster in Matt Wedel’s Binocular Highlight column in the May Sky & Telescope, page 43.
MONDAY, MAY 18
■ This evening waxing crescent Moon will shine just 2° or 3° from Venus, as shown below. Such a striking couple they’ll make! They will turn the heads of your non-astronomical friends and family anywhere in the Americas — where they will appear closer together at the time of dusk than elsewhere around the world.
TUESDAY, MAY 19
■ This evening, the waxing Moon forms the latest of its monthly quadrilaterals with Jupiter, Pollux, and Castor, as shown above. Down to their lower right shines Venus.
WEDNESDAY, MAY 20
■ Tonight the Moon shines upper left of Jupiter and Venus in the darkening dusk, as shown above. The Moon makes an isosceles triangle (two equal sides) with Jupiter and Pollux.
THURSDAY, MAY 21
■ Vega, the Summer Star, is now nicely up in the east-northeast after dark. Look for its faint little constellation Lyra, the Lyre, hanging down from it with its bottom canted to the right. Lyra’s main pattern consists of a little equilateral triangle with Vega as one corner, and a larger parallelogram attached to the triangle’s bottom corner.
FRIDAY, MAY 22
■ First-quarter Moon this evening and tomorrow evening; the Moon is exactly first-quarter at 7:11 a.m. Eastern Daylight time tomorrow morning the 23rd, about halfway between the two evenings.
■ This evening, spot 1st-magnitude Regulus just a couple degrees to the Moon’s upper left (for North America). The Sickle of Leo extends almost directly right from Regulus now, with its cutting edge facing down. The Sickle is a little more than a fist at arm’s length long.
SATURDAY, MAY 23
■ With the Moon just a half day past first quarter (for the Americas), the terminator between lunar day and night still crosses almost perfectly straight across the Moon’s face. In a telescope this evening the terminator crosses interesting terrain. After dark (again for the Americas) it’s beginning to uncover Mare Imbrium in the north, highlighting the crater pair Aristillus and Autolycus on Imbrium’s flat floor. Framing them are the Alps and Apennines, some of the Moon’s highest mountains, along Imbrium’s rim. Farther south, the terminator highlights some of the largest craters of the Southern Highlands, with more to show up tomorrow.
SUNDAY, MAY 24
■ Have you ever seen even one star of Centaurus? Alpha Centauri, famous and bright, never gets above the horizon unless you’re as far south as San Antonio or Orlando (latitude 29° N). But Theta Centauri, shining at a respectable magnitude 2.0, clears your south horizon anywhere in the continental United States and southern Canada. No other star in its area is as bright.
But you have to know where and when to look.
In late May, the time comes about an hour after the very end of twilight. And the place? Theta Centauri is due south almost three fists (27°) lower left of Spica, and just a bit farther (32°) right of Antares and a bit lower. You’ll need an open view very low to the south; the farther north you are, the lower. Binoculars will help through light pollution near your south horizon and/or if Theta Cen is so low that atmospheric extinction dims it a lot. Catch it and that’s one more constellation, or at least a piece of one, to add to your life list.
This Week’s Planet Roundup
Mercury is out of sight in inferior conjunction with the Sun.
Venus (magnitude –3.9) shines bright white in the west-northwest during evening twilight. Venus is about as high now as we’re going to see it during this rather low apparition. It doesn’t set until about 50 minutes after complete dark.
High to Venus’s upper left shines Jupiter. A somewhat similar distance to Venus’s upper right sparkles Capella.
As the stars come out closer to Venus, just a few finger widths from it you’ll find the horntip stars of Taurus: Beta Tauri and lesser Zeta Tauri. On Friday the 15th Venus is a little above the midpoint between them. Day by day they’ll slide farther to the lower right behind Venus, making the triangle grow taller and taller.
On Monday May 18th the waxing crescent Moon shines just 2° or 3° from Venus for the Americas. At the time of dusk elsewhere, the two will be farther apart. Think photo opportunity.
Mars and Saturn are still low in the east in the brightening dawn; bring binoculars. Saturn is the higher and brighter of the two, magnitude +0.9. Mars is much lower and somewhat fainter, magnitude +1.3. Look for Mars almost two fists to Saturn’s lower left, a little farther every morning.
Jupiter, magnitude –1.9 in Gemini, is the second-brightest planet after Venus. It shines in the west in twilight about 25° to Venus’s upper left. Watch the two planets close in toward each other for the next few weeks! At their conjunction on June 9th, they’ll pass just 1.6° apart.
Look upper right of Jupiter for Pollux and Castor, and farther lower left of Jupiter for Procyon. Jupiter sinks through the evening and sets around midnight on the west-northwest horizon.
In a telescope Jupiter is down to 34 arcseconds wide, nearly as small as we ever see it; Earth is carrying us around toward the far side of the Sun from it.
I’ve certainly been fooled! Once when I was using my 12.5-inch reflector and knew the situation beforehand, dark Callisto did seem to look a little grayer than a shadow might. But in astronomy, contrast can sure play tricks. The opposite effect happens when you see our own dark-surfaced Moon sunlit against a darker sky. It looks brilliant white.
For a timetable of all the doings of Jupiter’s moons this month, good worldwide, see the May Sky & Telescope, page 51.
Uranus is in conjunction with the Sun.
Neptune hides low before dawn.
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 also known as UTC, GMT, or Z time.
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.
For the attitude every amateur astronomer needs, read Jennifer Willis’s Modest Expectations Give Rise to Delight.
Once you get a telescope, to put it to good use you’ll want 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. Both show all 30,000 stars to magnitude 7.6, and 1,500 deep-sky targets — star clusters, nebulae, and galaxies — to search out among them.
Next up is the larger and deeper Sky Atlas 2000.0, plotting stars to magnitude 8.5; nearly three times as many, as well as many more deep-sky objects. It’s currently out of print, but maybe you can find one used.
The next up, once you know your way around well, are the even larger Interstellarum Deep-Sky Atlas (with 201,000+ stars to magnitude 9.5 and 14,000 deep-sky objects selected to be detectable by eye in very large amateur telescopes), and Uranometria 2000.0 (332,000 stars to mag 9.75, and 10,300 deep-sky objects).
For the necessary tricks, read How to Use a Star Chart with a Telescope. It applies just as much to electronic charts on your phone or tablet — which many observers find handier and more versatile, if sometimes less well designed and contextualized For the necessary tricks, read How to Use a Star Chart with a Telescope. It applies just as much to electronic charts on your phone or tablet — which many observers find handier and more versatile, if sometimes less well designed and contextualized — as it does 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. It was my bedside reading for years. An impressive more modern one is the big Night Sky Observer’s Guide set (2+ volumes) by Kepple and Sanner. The pinnacle for total astro-geeks is the new Annals of the Deep Sky series, currently at 11 volumes as it works its way forward through the constellations alphabetically. So far it’s up to H.
Can computerized telescopes replace charts? Well, I used to say this:
“Not for beginners, I don’t think, unless you prefer spending your time getting finicky technology to work rather than learning how to explore through the sky yourself. 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 and a curious mind.’ Without these, ‘the sky never becomes a friendly place.’ “
But things change. The technology has continued to improve and become more user-friendly — particularly with “plate solving” software that can now recognize any star field to determine exactly where the telescope is pointed — finally bypassing all aiming imperfections in the mount, tripod, gears, bearings and other mechanics, or in the user’s skill in setting up.
The latest revolution is the rise of small, photography-only “smartscopes.” These take advantage of not only today’s pointing technology, but also the vastly better capabilities of imaging chips and image processing compared to the human retina and visual cortex. The most sophisticated image stacking and processing can come built right in. The result is decent deep-sky imaging from shockingly small, low-priced units. The image may be viewable on your phone or computer as it builds up in real time. Some can directly enable contributions to citizen-science projects.
Smartscopes are changing the hobby at the entry level. For more on this see Richard Wright’s “The Rise of the Smart Telescopes” in the November 2025 Sky & Telescope. And read the magazine’s review of this especially small one.
If you get a larger, more conventional computerized scope that you can look through, make sure that its drives can be disengaged so you can swing it around and point it readily by hand when you want to, rather than only slowly by the electric motors (which eat batteries).
Audio sky tour. Out under the evening sky with your
earbuds in place, listen to Kelly Beatty’s monthly
podcast tour of the naked-eye heavens above. It’s free.
“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, The Demon-Haunted World: Science as a Candle in the Dark
“Facts are stubborn things; and whatever may be our wishes, our inclinations, or the dictates of our passion, they cannot alter the state of facts and evidence.”
— John Adams, 1770, in the summation of his unpopular, but successful, defense of British soldiers in the Boston Massacre trial
“Truly, whoever can make you believe absurdities can make you commit atrocities.”
— Voltaire, 1765, Questions sur les miracles