FRIDAY, JULY 17
■ In the western sky at dusk, Venus shines less than half a fist to the right of the Moon, as shown below.
These are the two brightest celestial objects after the Sun. Sometimes they are also the nearest two that are visible to the naked eye. But not now. Although the Moon is a crescent, a telescope reveals Venus to be gibbous, even though they stand in the same part of the sky. Why? Because the Moon is closer to us than the Sun is, so we see more of the Moon’s night side. But Venus is now on the far side of the Sun from us, so we see more of its daylit side. Mercury and the Sun are closer.
SATURDAY, JULY 18
■ Starry Scorpius is sometimes called “the Orion of Summer” — for its brightness, its blue-white giant stars, and its prominent red supergiant (Antares in the case of Scorpius, Betelgeuse for Orion). But Scorpius passes a lot lower across the southern sky than Orion does, for those of us at mid-northern latitudes. That means it has only one really good evening month: July.
The rich area around the tail of Scorpius is now at its best low in the south soon after night is fully dark, as shown below. Find it about a fist and a half at arm’s length lower left of Antares. Or, a fist or less lower right of the spout of the Sagittarius Teapot. How high or low this whole scene will appear depends on how far north or south you live: the farther south, the higher.
And the Cat’s Eyes point west (right) to Mu Scorpii, a much closer pair known as the Little Cat’s Eyes.
Stellarium
SUNDAY, JULY 19
■ The eyes in the tail. Spot the Cat’s Eyes in Scorpius’s tail, shown above. They are Shaula and Lesath, Lambda and Upsilon Scorpii. They’re unequal and canted at an angle; the cat has a bleary eye and is tilting his head to our right. They’re magnitudes 1.6 and 2.6. Both are blue-white supergiants, 700 and 500 light years away, respectively. The fainter one, Lesath, is the nearer one.
Between the Cat’s Eyes and the Teapot’s spout are the open star clusters M7 and M6, speckle-splashes in binoculars. M7 is the bigger and brighter one; M6 is much less of a standout.
Also: A line through the Cat’s Eyes points side-eye to the right (west) by nearly a fist toward Mu Scorpii, a much tighter pair known as the Little Cat’s Eyes. They’re oriented almost exactly the same way as Lambda and Upsilon, but they’re only 0.1° apart, so they appear as a single dot on the chart above; bring binoculars. They too are not a true binary. They’re 800 and 500 light-years away, and again the fainter one is nearer.
For a deep-sky tour all along the July evening Milky Way, see Bob King’s Steamy Nights at the Galactic Equator.
MONDAY, JULY 20
■ First-quarter Moon this evening and tomorrow evening. It’s exactly first quarter at 7:06 a.m. EDT Tuesday morning, about halfway between the two evenings for the Americas. Notice that the Moon’s terminator is not quite straight: slightly concave this evening, slightly convex tomorrow evening.
■ This evening Spica shines about 3° above the Moon. Spot brighter Arcturus about three fists higher up in twilight. Later in the evening it’ll be upper right of the Moon.
TUESDAY, JULY 21
■ Now the Moon shines about a fist left of Spica: a quarter of the way from 1st-magnitude Spica to 1st-magnitude Antares. Every month the Moon takes just about 4 days to make the trip from Spica east to Antares.
WEDNESDAY, JULY 22
■ We’re only a third of the way through summer, but already Cassiopeia is getting well up after dark. Look for its tilted W pattern in the north-northeast.
High above it is dimmer Cepheus. Below it, the head of Perseus is on the rise. The farther north you live the higher they all will appear.
THURSDAY, JULY 23
■ After nightfall Altair shines high in the southeast. It’s the brightest star on the eastern side of the sky, not counting Vega high above it almost overhead.
Above Altair by a finger-width at arm’s length is little orange Tarazed (Gamma Aquilae), Altair’s eternal sidekick. It’s a modest magnitude 2.7 compared to Altair’s showy 0.7. But looks are deceiving. Altair looks so bright because it’s one of our near neighbors, just 17 light-years away. Tarazed is an orange giant star about 380 light-years farther in the background — and it’s 170 times as luminous as Altair.
FRIDAY, JULY 24
■ The waxing Moon has now made it to the neighborhood of Antares, as shown below.
■ Fourth star of the Summer Triangle. The brightest star that’s fairly near the Summer Triangle, if you’d like to turn it into a big diamond, is Rasalhague (Alpha Ophiuchi), the head of Ophiuchus. Look very high toward the southeast after dark, and the scene will be like this:
SATURDAY, JULY 25
■ As summer progresses, bright Arcturus moves down the western side of the evening sky. Its pale ginger-ale tint always helps identify it.
Arcturus forms the bottom point of the Kite of Boötes. The Kite, rather narrow, extends upper right from Arcturus by 23°, about two fists at arm’s length. The lower right side of the kite is dented inward, as if some invisible celestial intruder once banged into it.
SUNDAY, JULY 26
■ More Arcturus. Look again to Arcturus high in the west. In astronomy lore today, Arcturus may be best known for its cosmic history: It’s an orange giant some 7 billion years old, older than the solar system, racing by our part of space on a trajectory that indicates it was born in another galaxy: probably one of the many dwarf galaxies that fell into the Milky Way and merged with it.
But in the astronomy books of our grandparents, Arcturus had a different claim to fame: It turned on the lights of the 1933 World’s Fair in Chicago, launching its celebration of “a century of progress.” Astronomers rigged the newly invented photocell to the eye end of big telescopes around the US and aimed them where Arcturus would pass at the appointed moment on opening night. Where the sky was clear the star’s light crept onto the cells, the weak signals were amplified and sent over telegraph wires to Chicago, and on blazed the massive lights to the cheers of tens of thousands.
Why Arcturus? Astronomers at the time thought it was 40 light-years away (modern value: 36.7 ±0.2). So the light would have been in flight since the previous such great event in Chicago, the World’s Columbian Exhibition in 1893.
And earlier? Arcturus was famous as one of the first stars discovered to show proper motion, its own independent motion on the celestial sphere. In 1718 Edmond Halley realized that Arcturus, Sirius, and Aldebaran had moved more than half a degree from where the Greek astronomer Hipparchus measured them to be some 1,850 years earlier.
And before that? Arcturus was the first nighttime star that anyone saw in the daytime with a telescope: by Jean-Baptiste Morin in 1635.
This Week’s Planet Roundup
Mercury emerges low into dawn view late this week. Look for it very low above the east-northeast horizon about 40 minutes before sunrise. It’ll be faint as Mercury goes, but it will brighten daily as well as get a little higher. (Don’t confuse it with fainter Castor or Pollux about a fist to its left.)
Venus shines brightly (magnitude –4.2) as the “Evening Star” low in the west in twilight. It’s getting just a little lower every week and sets around the end of twilight.
In a telescope, Venus is a brilliant, slightly gibbous disk 19 arcseconds from pole to pole. Catch it as soon in late afternoon or early dusk as you can, before it sinks low into poorer atmospheric seeing.
Venus will remain in twilight view until the end of the summer, gradually lower, enlarging while waning in phase.
Mars (magnitude +1.3, in Taurus) glows in the east in early dawn. Aldebaran, its near-twin for brightness and color, twinkles to its right, and fainter Beta Tauri twinkles to Mars’s left. Mars passes exactly midway between the two leading stars of Taurus on Wednesday morning July 22nd. It will form a straight line with them, 8.4° from each.
Mars is still on the far side of its orbit from us, so in a telescope it’s only a tiny, fuzzy blob 4½° arcseconds wide.
Jupiter is hidden in conjunction with the Sun.
Saturn (magnitude +0.6, at the Pisces-Cetus border) rises in the east around 11 or midnight. Once it’s up, find it below the Great Square of Pegasus, which is balanced on one corner. Saturn is well placed for telescopic viewing high in the southeast before dawn. It’s the brightest thing in its dim area. (Don’t confuse it with Fomalhaut, its near-twin in brightness, twinkling four fists down to Saturn’s lower right.)
Late last fall Saturn’s rings turned nearly edged-on to Earth and almost disappeared. Now the rings’ inclination has widened back up to 9°.
Uranus (magnitude 5.8, in Taurus) hides in the distance about 12° west of Mars.
Neptune (magnitude 7.9, at the Pisces/Cetus border) hides even farther in the background 10° west of Saturn. You’ll need detailed finder charts to tell Uranus and Neptune from background stars of similar brightness.
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.
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 units, relatively low priced. 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