Astronomy Picture Of The Day

On April 20, 2023 the shadow of a New Moon raced across planet Earth’s southern hemisphere. When viewed along a narrow path that mostly avoided landfall, the Moon in silhouette created a hybrid solar eclipse. Hybrid eclipses are rare and can be seen as a total eclipse or an annular “ring of fire” eclipse depending […]

Gorgeous spiral galaxy NGC 3521 is a mere 35 million light-years away, toward the northern springtime constellation Leo. Relatively bright in planet Earth’s sky, NGC 3521 is easily visible in small telescopes but often overlooked by amateur imagers in favor of other Leo spiral galaxies, like M66 and M65. It’s hard to overlook in this […]

Why would the sky glow like a giant repeating rainbow? Airglow. Now, air glows all of the time, but it is usually hard to see. A disturbance  however — like an approaching storm — may cause noticeable rippling in the Earth’s atmosphere. These gravity waves are oscillations in air analogous to those created when a rock is thrown in […]

What’s happening to this spiral galaxy? Although details remain uncertain, it surely has to do with an ongoing battle with its smaller galactic neighbor. The featured galaxy is labelled UGC 1810 by itself, but together with its collisional partner is known as Arp 273. The overall shape of UGC 1810 — in particular its blue […]

Savudrija lighthouse shines along the coast near the northern end of the Istrian peninsula in this well-composed night skyscape. A navigational aid for sailors on the Adriatic Sea, the historic lighthouse was constructed in the early 19th century. But an even older aid to navigation shines in the sky above, Polaris, alpha star of the […]

What’s happening in the center of spiral galaxy NGC 2566? First, the eight rays that appear to be coming out of the center in the featured infrared image are not real — they are diffraction spikes caused by the mechanical structure of the Webb space telescope itself. The center of NGC 2566 is bright but […]

This might look like a double-bladed lightsaber, but these two cosmic jets actually beam outward from a newborn star in a galaxy near you. Constructed from Hubble Space Telescope image data, the stunning scene spans about half a light-year across Herbig-Haro 24 (HH 24), some 1,300 light-years or 400 parsecs away in the stellar nurseries […]

The red flowery-looking nebula just above the image center may seem a good choice, but that’s not it. The famous Rosette Nebula is really located on the lower right, here colored blue and white, and connected to the other nebulas by gold-colored filaments. Because the featured image of Rosette’s field is so wide, and because […]

The bright clusters and nebulae of planet Earth’s night sky are often given the names of flowers or insects, and its whopping 3 light-year wingspan, NGC 6302 is no exception. With an estimated surface temperature of about 250,000 degrees C, the central star of the planetary nebula is transforming into a white dwarf star, becoming […]

Jupiter is stranger than we knew. NASA’s Juno spacecraft has now completed over 70 swoops past Jupiter as it moves around its highly elliptical orbit. Pictured from 2017, Jupiter is seen from below where, surprisingly, the horizontal bands that cover most of the planet disappear into swirls and complex patterns. A line of white oval clouds […]

Deimos takes 30 hours and 18 minutes to complete one orbit around the Red Planet. That’s a little more than one Martian day or sol which is about 24 hours and 40 minutes long, so Deimos drifts westward across the Martian sky. About 15 kilometers across at its widest, the smallest of Mars’ two moons […]

Most globular star clusters roam the halo of our Milky Way galaxy, but globular cluster NGC 6366 lies close to the galactic plane. About 12,000 light-years away toward the constellation Ophiuchus, the cluster’s starlight is dimmed and reddened by the Milky Way’s interstellar dust when viewed from planet Earth. As a result, the stars of […]