Table of contents for July 2025 in Astronomy

TWO FOR ONE Two NASA missions, SPHEREx and PUNCH, launched March 11 from Vandenberg Space Force Base on a SpaceX Falcon 9 rocket. SPHEREx will map the near-infrared sky and millions of galaxies, while PUNCH will study the Sun’s corona and solar wind. AURORAE UNVEILED NASA’s James Webb Space Telescope has captured the first images of bright auroral activity on Neptune. The data show the ice giant’s upper atmosphere has cooled by hundreds of degrees since Voyager 2’s 1989 flyby, making the aurorae fainter than expected. FIRST FLIGHT FIZZLES Isar Aerospace’s first test flight March 30 from Norway’s Andøya Spaceport was also the first orbital launch ever attempted from mainland Europe. The rocket lifted off successfully, but lost control about 20 seconds after launch and fell into the sea near…

GALACTIC DISCO BALL The disk of gas and dust surrounding the Milky Way’s central black hole lights up with continuous flares, finds JWST in research published Feb. 18. The bursts of light are thought to be analogous in nature to solar flares. ANCIENT IMPACT Researchers have discovered what could be Earth’s oldest known impact crater, in Western Australia’s Pilbara region. The over-60-mile-wide (100 km) feature is an estimated 3.5 billion years old, predating the previous recordholder by 1.3 billion years. LIFE’S TINY SPARK A Stanford University team has found that when sprayed, water droplets collide and produce electrical charges that cause “microlightning,” which forms organic molecules essential for life. This suggests life could have formed on early Earth through crashing waves, not lighting strikes, as previously proposed. CHINA’S PLANETARY PLANS…

Visible to the naked eye Visible with binoculars Visible with a telescope JULY 2025 Venus tracks through Taurus Summer nights offer lots of interesting sights this month. Mercury and Mars are on show in the evening twilight. Both Uranus and Neptune stand near brighter beacons: Neptune and Saturn are two Moonwidths apart all month, while the morning sky hosts Venus and Uranus together in Taurus. Saturn also shows off two Titan shadow transits, visible through small telescopes. Jupiter returns late in the month, as Pluto reaches opposition. Mercury hangs low in the west soon after sunset, shining brightly at magnitude 0.4. It outshines Regulus, Leo’s brightest star, by a full magnitude. Mercury stands 1° southwest of the Beehive Cluster (M44) on the 2nd. If you have a clear western horizon…

WHEN COMET C/2023 A3 (Tsuchinshan-ATLAS) reached magnitude–6 last October, why was Venus, two magnitudes fainter, easier to see? A more compact light source punches through skyglow, while diffuse light from an expansive comet tail is too faint to compete with the twilight. A comet’s integrated magnitude comes from adding together the light from its tail as if it were compressed into a star. Comet discoverer David Levy recommends the in-out method to visually estimate a comet’s total brightness at the telescope. In a nutshell, study the comet’s in-focus apparent size and average brightness through the eyepiece. Now find a slightly brighter star, take it out of focus to make it the size of the comet, and compare. Jump to different stars until you get a reasonable match. Notice how much…

1. A GALACTIC MEGACONGLOMERATE The galaxy Fornax A (NGC 1316) is famed for its enormous radio lobes, but deep optical imaging reveals dizzying layers of structure generated by a series of mergers that made the galaxy what it is today. Just right of Fornax A is the smaller spiral NGC 1317, likely to be the larger galaxy’s next acquisition. The imagers used a 20-inch reflector to collect 43 hours of LRGB data. • Team ShaRA 2. A (REALLY) LONG EXPOSURE In this solargraph, the Sun’s journey across the sky is captured continuously for 43 days, its trails interrupted by overcast days and passing clouds. To create the image, the photographer transformed a beer can into a pinhole camera and lined the interior with light-sensitive photographic paper. In the foreground is…

The constellation Andromeda the Princess is part of the largest mythologically connected group in the sky. Her parents are Cepheus the King and Cassiopeia the Queen. Perseus the Hero saved her from being sacrificed to Cetus the Whale (a sea monster in the tale). And Pegasus the Winged Horse was born when Perseus cut off the Gorgon Medusa’s head. Andromeda is best viewed in the early evening during the first two weeks of October when — from our perspective — it lies across the sky from the Sun. It’s invisible around early April when it lines up with our daytime star. The Princess is above average in size, ranking 19th among the 88 constellations, and near the middle (37th) in overall brightness. Interestingly, its brightest star, Alpheratz (Alpha [α] Andromedae),…

Swing low THERE’S A SHIFTING PATTERN of moonrises at Full phase that caught the eyes of the ancients. It’s just finished bottoming out, making an easy start for you to ride the wave of the next 18.6-year cycle. Echoing the way winter sunrises head to the southeast, stop at the solstice, and return northward, Luna’s summer moonrises do the same but with a surprise. This year, the moonrises are an extra 7° farther south, quite a lot for an avid watcher of the skies. Halfway into the cycle — in 2034 — they will fall 7° closer to the east. It’s easier to notice this lunar standstill when you have prominent features at the horizon, like hills or notches, or distant trees or buildings. Most importantly, you’ll need a viewing…

WHEN YOU CAN’T TAKE THE TIME for a full session, even 10 minutes of observing helps you relax after a long day and before the next one. Step outside with binoculars and you’ll be seeing asteroid 4 Vesta within a few breaths. Familiarize yourself with Alpha (α) and Beta (β) Librae almost due south as twilight fades, halfway between luminaries Spica and Antares. It will take six weeks for Vesta to split these stars, time for you to have a quick peek every three or four nights and notice it shift toward Antares. As July opens, Vesta lies between the feet of Virgo, Mu (μ) and Kappa (κ) Virginis, a fainter echo of Libra’s lights. If you’re using a scope to follow the main-belt world, give the distant globular cluster…

This is a tale of rediscovery. I have been an astronomer for more than half a century. My current observing concentrates on showcase nebulae and galaxies or the pursuit of fine lunar detail. But recently, I had a reawakening that transported me back to when I received my first “serious” telescope, a 4-inch reflector, at Christmas 1960. At the time, I lived on a ranch midway between San Antonio and Laredo, Texas. To say that night sky was dark is to reminisce about what few modern astronomers have experienced. My other Christmas gift, Antonin Becvar’s Atlas of the Heavens, was hot off the press. I saw the thousands of New General Catalogue (NGC) objects plotted in the atlas as a roadmap to the stars. The real-world sky The NGC is…

Mobile mount Vixen Saitama, Japan The Mobile Porta Mount is the new, easily portable piece in the popular Porta line. The altazimuth accessory has friction stop motion to locate objects quickly. Telescopes weighing up to 7.7 pounds (3.5 kilograms) can be attached. The mount head can be detached and the multiarm can be folded, both for ultimate portability. $215.99 1-866-252-3811 https://global.vixen.co.jp/ Fact and fiction Reaktion Books London, United Kingdom In Amazing Worlds of Science Fiction and Science Fact, science journalist Keith Cooper explores the exoplanets found in popular media. Over a dozen scientists and authors weigh in as Cooper analyzes how realistic the fictional planets are in Star Wars, Avatar, Dune, and more. The 224-page book also contains 12 illustrations. $22.50 info@reaktionbooks.co.uk https://reaktionbooks.co.uk Small and strong ZWO Suzhou, China Seestar…

As stars form, they pull in material from their surroundings. But they also spew out jets of gas and dust, as seen in this James Webb Space Telescope image of Lynds 483. At the center of the jets is a pair of protostars, invisible within a disk of cold gas and surrounded by dense dust, which is noticeable by the way it dims the light of stars far behind this system to either side. Over time, the stars have blown out material that has formed the jets at the top and bottom. Visible features include a shock front, shown in orange at upper right, where the jet has run into denser interstellar material and slowed. Asymmetries and other structural details in the jets allow astronomers to trace the stars’ past…

AS IT FLEW BY MARS March 12, the European Space Agency’s flagship planetary defense mission Hera snapped pictures of the moon Deimos. The flyby was a gravity assist to the mission’s final destination: the binary asteroid system Dimorphos and Didymos. But the mission also took the flyby as an opportunity to test some of its scientific equipment. Hera’s vantage point allowed it to survey the little-studied farside of the tidally locked 7.7-mile-wide (12.4 kilometers) moon. This black-and-white image was taken by Hera’s Asteroid Framing Camera. Once Hera arrives at its destination, the camera will image the impact crater left in 2022 by NASA’s Double Asteroid Redirection Test.…

Southern Delta Aquariid meteor shower SOUTHERN DELTA AQUARIID METEORS Active dates: July 12–Aug. 23 Peak: July 31 Moon at peak: Waxing crescent Maximum rate at peak: 25 meteors/hour THE SUMMER meteor season begins in July. The combination of a few minor showers with low hourly rates contributes to a strong chance of catching a meteor during the dark moonless hours of night. The Southern Delta Aquariids are active starting the 12th and build slowly through the first three weeks of July. Near the peak on July 31, if the radiant were overhead it would produce about 25 meteors per hour. The radiant is near the 3rd-magnitude star Skat in Aquarius, and climbs to 25° altitude from North America in the hour before dawn. Watch for maybe a dozen meteors per…

The evening sky boasts two naked-eye planets. Start your night’s viewing with ruddy Mars, which lies in the west as darkness falls. It treks eastward against the backdrop of Virgo, passing 2° north of the Maiden’s brightest star, 1stmagnitude Spica, on Sept. 12. The Red Planet shines at magnitude 1.6, slightly fainter than the blue-white star. Mars lies far from Earth, unfortunately, so it doesn’t look like much through a telescope. It sports a featureless disk 4" in apparent diameter. On the other side of the evening sky resides September’s gem, Saturn. The ringed world reaches opposition and peak visibility Sept. 21, when it lies opposite the Sun in our sky and remains visible all night. The magnitude 0.6 planet moves slowly westward against the background stars of southern Pisces…