This Week’s Sky at a Glance, April 26 – May 4


Saturn and Sagittarius in early dawn, late April and early May 2019

All this week, Saturn remains almost stationary with respect to the Sagittarius Teapot in early dawn and before. The blue 10° scale is about the width of your fist at arm's length.

Friday, April 26

• Last-quarter Moon (exact at 6:18 p.m. EDT). The Moon rises very late tonight, around 3 a.m. daylight-saving time, in the center of the dim, boat-shape pattern of Capricornus. High above the Moon is Altair. The brightest "stars" far to the Moon's right or upper right are Saturn, then brighter Jupiter.

Saturday, April 27

• As night descends, look high in the west for Pollux and Castor lined up almost horizontally (depending on your latitude). These two stars, the heads of the Gemini twins, 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. The whole thing sinks lower 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 Hawaiian Canoe-Bailer of Makali‘i.

Sunday, April 28

• As the last of twilight fades out, the dim Little Dipper extends to the right from Polaris. High above the Little Dipper's bowl (marked by Kochab, Polaris's equal in brightness), you'll find the bowl of the Big Dipper.

Sickle of Leo

Sickle of Leo

Monday, April 29

• Just after dark, the Sickle of Leo stands vertical high in the south. Its bottom star is Regulus, the brightest of Leo. In second place is yellow Algieba above it.

Leo himself is walking horizontally westward. The Sickle forms his front leg, chest, mane, and part of his head. Denebola, about two and a half fists at arm's length left of Regulus, is his tail-tip.

Tuesday, April 30

• Arcturus is the brightest star high in the east these evenings. Spica shines lower right of it by about three fists. To the right of Spica by half that distance is the distinctive four-star constellation of Corvus, the Crow of Spring.

Wednesday, May 1

• It's May now, but wintry Sirius still twinkles very low in the west-southwest at the end of twilight. It sets soon after. How much longer into the spring can you keep Sirius in view? In other words, what will be its date of "heliacal setting" as seen by you?

Thursday, May 2

• Summer is more than six weeks away, but the Summer Triangle is beginning to make its appearance in the east, one star after another. The first in view is Vega. It's already visible low in the northeast as twilight fades.

Next up is Deneb, lower left of Vega by two or three fists at arm's length. Deneb takes about an hour to appear after Vega does, depending on your latitude.

The third is Altair, which shows up far to their lower right around midnight.

Friday, May 3

• Three zero-magnitude stars shine after dark in May: Arcturus high in the southeast, Vega much lower in the northeast, and Capella in the northwest. They appear so bright because each is at least 60 times as luminous as the Sun, and because they're all relatively nearby: 37, 25, and 42 light-years from us, respectively.

Saturday, May 4

• Vega is the brightest star in the northeast late these evenings. Look 14° (about a fist and a half at arm's length) to Vega's upper left for Eltanin, the nose of Draco the Dragon. Closer above and upper left of Eltanin are the three fainter stars of Draco's stick-figure head, also called the Lozenge. Draco always points his nose to Vega no matter how we see them. He seems awfully curious about it. A jewel for dragon food?

The faintest star of Draco's head, opposite Eltanin, is 4th-magnitude Nu Draconis. It's a lovely, equal-brightness double star for binoculars and small scopes (separation 61 arcseconds).

• New Moon (exact at 6:46 p.m. EDT).


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.

Jumbo Pocket Sky Atlas cover

The Pocket Sky Atlas plots 30,796 stars to magnitude 7.6, and hundreds of telescopic galaxies, star clusters, and nebulae among them. Shown above is the Jumbo Edition for easier reading in the night. Sample chart.

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.

You'll also want a good deep-sky guidebook, such as Sue French's Deep-Sky Wonders collection (which includes its own charts), Sky Atlas 2000.0 Companion by Strong and Sinnott, or the bigger Night Sky Observer's Guide 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 (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."

Mercury imaged with the 1-meter Chilescope

"You can't see detail on Mercury." That's been a truism for amateurs visually, but it's not true for skilled astrophotographers, especially if they're using the 1-meter (40-inch) Chilescope remotely. Damian Peach caught this richly detailed image of Mercury's surface on the morning of April 8th. The current apparition of Mercury is poor for viewers in  the Northern Hemisphere but good for the Southern Hemisphere.

Jupiter with Great Red Spot, April 15, 2019

Jupiter's Great Red Spot was on the planet's central meridian (System II longitude 309°) when Christopher Go took this image on April 15th with a 14-inch Schmidt-Cass. South is up. Left of (preceding) the GRS, the south edge of the South Equatorial Belt is very dark. On the following side of the GRS this feature is missing.
As I usually do, I've brightened Go's image to look a bit more like Jupiter does in a telescope. To mimic Jupiter's appearance in amateur scopes of various sizes (in very steady seeing), turn your screen to maximum brightness and view this image from the far side of the room while squinting your eyes to various degrees. Study the view as carefully as you can; take your time. What are the very finest details you detect that turn out to be real when you come close to check?

Saturn on April 7, 2019

Saturn by Peach on April 7th, also taken with the Chilescope. South is up. Stacked-video images of Saturn can be tricky to process without creating false artifacts, due to their many high-contrast borders between bright and dark. Peach's seem to be practically free of them. For instance, the thin Encke Gap near the outer edge of the outer A ring is recorded unambiguously. Note the North Polar Hexagon and its tiny central dot.

The Venus-Mercury challenge gets even tougher! Venus (magnitude –3.9) and much fainter Mercury (about magnitude –0.3) are both very low in the brightening dawn. Pick up Venus just above the due-east horizon about 20 minutes before sunrise. Then use binoculars or a wide-field telescope to look for little Mercury a good 6° to 8° to its lower left. Good luck.

Mars (magnitude +1.6, in Taurus) glows in the west during and after dusk, lower every week now. Spot it about 20° to the right of brighter, Mars-colored Betelgeuse – the topmost bright star of departing Orion. In a telescope Mars is a hopeless little blur-blob (4½ across); it's almost as far from Earth as it ever gets.

Jupiter (magnitude –2.4, at the eastern foot of Ophiuchus) rises in the southeast around 11 or midnight daylight-saving time. It shines highest in the south before dawn begins, so that's the best time to observe it telescopically. Jupiter has grown to a good 43 arcseconds wide (equatorial diameter) as it creeps toward its June 10th opposition. See Richard Jakiel's Jupiter observing guide in the May Sky & Telescope, page 52.

Saturn (magnitude +0.6, in Sagittarius) rises around 1 a.m. As dawn begins, it's the "star" 27° (almost three fists at arm's length) to Jupiter's left.

Uranus is hidden in conjunction with the Sun.

Neptune is still deep 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.


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.


"We may be little guys, but we don’t think small. It’s the courage of questions, of grasping our true circumstances, and not pretending we are at the center of it all, that is adulthood."
– Ann Druyan, 2014



4 thoughts on “This Week’s Sky at a Glance, April 26 – May 4

  1. RodRod

    “Monday, April 29• Just after dark, the Sickle of Leo stands vertical high in the south. Its bottom star is Regulus, the brightest of Leo. In second place is yellow Algieba above it.” My note – Algieba (Gamma Leonis) is a fine double star system to view using small telescopes. On 24-April-19 near 2100 EDT, I enjoyed some very good views of this double star system using my 90-mm refractor at 71x. The two stars are separated by about 4.7 arcsecond and at a distance of about 126 light-years from earth (stellar parallax published), the angular separation is more than 170 astronomical units (177-178 au). These two stars may be a binary system with orbital period near 510 years. I also enjoyed views of sunspot AR2738 recently with an angular size 53 arcseconds or more, some 3x larger diameter than Earth. It is fun to compare views in the telescope like this and the differences in measurements that point to the immense size of some sunspots compared to earth as well as the distance and size of double stars as seen from earth.

  2. RodRod

    mary beth, any stargazing? Last night I was out from 2200-0015 EDT. I can report a Vega sighting in Lyra 🙂 I enjoyed globular clusters using my 10-inch Newtonian. M13 and M92. 4 galaxies in Virgo. M87, and a nice trio, M84, M86, and NGC 4388. I had clear skies and temp 7C. I also enjoy grass cutting and weed whacking too 🙂

  3. mary bethmary beth

    We’ve had some clear nights and it’s been beautiful observing Orion sinking lower every night – just amazes me. Such a reliable clock and calendar! I don’t do any cutting or weed whacking but I am enjoying watching everything grow and turn so beautifully green! I sure love the scent of fresh mown grass. I always felt like the sunshine of May has a green tint to it! We are approaching ‘solar summer’ – The quarter of the most sunshine, May 7 through August 7 I believe! My birthday is May 4 and I always think of it as such a sunny day. I bet I have only had three or four rainy days my whole long life LOL. Glad you got to enjoy Vega!

  4. RodRod

    mary beth, good to hear some clear skies. Enjoy your birthday 🙂 We have clouds and rain moving in later tonight and periodic remainder of this week. I did plenty of mowing and weed whacking today. My little *tractor* (large size ride mower) was tuned up recently for the season so is going strong. I need to keep the pastures cut and ready for my telescopes 🙂

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