Astronomy Picture of the Day

Light Echoes from V838 Mon
Image Credit: NASA, ESA, H. E. Bond (STScI)

Explanation: What caused this outburst of V838 Mon? For reasons unknown, star V838 Mon‘s outer surface suddenly greatly expanded with the result that it became one of the brighter stars in the Milky Way Galaxy in early 2002. Then, just as suddenly, it shrunk and faded. A stellar flash like this had never been seen before — supernovas and novas expel matter out into space. Although the V838 Mon flash appears to expel material into space, what is seen in the featured image from the Hubble Space Telescope is actually an outwardly expanding light echo of the original flash. In a light echo, light from the flash is reflected by successively more distant surfaces in the complex array of ambient interstellar dust that already surrounded the star. V838 Mon lies about 20,000 light years away toward the constellation of the unicorn (Monoceros), while the light echo above spans about six light years in diameter.

Tomorrow’s picture: gummy mountain stars


Astronomy Picture of the Day

Planets of the Solar System
Image Credit & Copyright: Antonio Canaveras, Chiara Tronci, Giovanni Esposito, Giuseppe Conzo, Luciana Guariglia, (Gruppo Astrofili Palidoro)

Explanation: Simultaneous images from four cameras were combined to construct this atmospheric predawn skyscape. The cooperative astro-panorama captures all the planets of the Solar System, just before sunrise on June 24. That foggy morning found innermost planet Mercury close to the horizon but just visible against the twilight, below and left of brilliant Venus. Along with the waning crescent Moon, the other bright naked-eye planets, Mars, Jupiter, and Saturn lie near the ecliptic, arcing up and to the right across the wide field of view. Binoculars would have been required to spot the much fainter planets Uranus and Neptune, though they also were along the ecliptic in the sky. In the foreground are excavations at an ancient Roman villa near Marina di San Nicola, Italy, planet Earth.

Tomorrow’s picture: echo monoceros

Astronomy Picture of the Day

Filaprom on the Western Limb
Image Credit & Copyright: Martin Wise

Explanation: A solar filament is an enormous stream of incandescent plasma suspended above the active surface of the Sun by looping magnetic fields. Seen against the solar disk it looks dark only because it’s a little cooler, and so slightly dimmer, than the solar photosphere. Suspended above the solar limb the same structure looks bright when viewed against the blackness of space and is called a solar prominence. A filaprom would be both of course, a stream of magnetized plasma that crosses in front of the solar disk and extends beyond the Sun’s edge. In this hydrogen-alpha close-up of the Sun captured on June 22, active region AR3038 is near the center of the frame. Active region AR3032 is seen at the far right, close to the Sun’s western limb. As AR3032 is carried by rotation toward the Sun’s visible edge, what was once a giant filament above it is now partly seen as a prominence, How big is AR3032’s filaprom? For scale planet Earth is shown near the top right corner.

Tomorrow’s picture: light-weekend

Astronomy Picture of the Day

Spiral Galaxy NGC 6744
Image Credit & Copyright: Basudeb Chakrabarti

Explanation: Beautiful spiral galaxy NGC 6744 is nearly 175,000 light-years across, larger than our own Milky Way. It lies some 30 million light-years distant in the southern constellation Pavo but appears as only a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight in this remarkably detailed galaxy portrait, a telescopic view that spans an area about the angular size of a full moon. In it, the giant galaxy’s elongated yellowish core is dominated by the light from old, cool stars. Beyond the core, grand spiral arms are filled with young blue star clusters and speckled with pinkish star forming regions. An extended arm sweeps past smaller satellite galaxy NGC 6744A at the lower right. NGC 6744’s galactic companion is reminiscent of the Milky Way’s satellite galaxy the Large Magellanic Cloud.

Tomorrow’s picture: pixels in space

Astronomy Picture of the Day

Supernova Remnant: The Veil Nebula
Image Credit & Copyright: Craig Stocks (Utah Desert Remote Observatories)

Explanation: Ten thousand years ago, before the dawn of recorded human history, a new light would have suddenly have appeared in the night sky and faded after a few weeks. Today we know this light was from a supernova, or exploding star, and record the expanding debris cloud as the Veil Nebula, a supernova remnant. Imaged with color filters featuring light emitted by sulfur (red), hydrogen (green), and oxygen (blue), this deep wide-angle view was processed to remove the stars and so better capture the impressive glowing filaments of the Veil. Also known as the Cygnus Loop, the Veil Nebula is roughly circular in shape and covers nearly 3 degrees on the sky toward the constellation of the Swan (Cygnus). Famous nebular sections include the Bat Nebula, the Witch’s Broom Nebula, and Fleming’s Triangular Wisp. The complete supernova remnant lies about 1,400 light-years away.

Tomorrow’s picture: open space

Astronomy Picture of the Day

Analemma over Taipei
Image Credit & Copyright: Meiying Lee

Explanation: Does the Sun return to the same spot on the sky every day? No. A better and more visual answer to that question is an analemma, a composite of images taken at the same time and from the same place over the course of a year. The featured analemma was compiled at 4:30 pm many afternoons from Taiwan during 2021, with the city skyline of Taipei in the foreground, including tall Taipei 101. The Sun‘s location in December — at the December solstice — is shown on the far left, while its location at the June solstice is captured on the far right. Also shown are the positions of the Sun throughout the rest of the day on the solstices and equinoxes. Today is the June solstice of 2022, the day in Earth‘s northern hemisphere when the Sun spends the longest time in the sky. In many countries, today marks the official beginning of a new season, for example winter in Earth’s southern hemisphere.

Tomorrow’s picture: big boom debris

Astronomy Picture of the Day

Rock Fingers on Mars
Image Credit: NASA, JPL-Caltech, MSSS

Explanation: There, just right of center, what is that? The surface of Mars keeps revealing new surprises with the recent discovery of finger-like rock spires. The small nearly-vertical rock outcrops were imaged last month by the robotic Curiosity rover on Mars. Although similar in size and shape to small snakes, the leading explanation for their origin is as conglomerations of small minerals left by water flowing through rock crevices. After these relatively dense minerals filled the crevices, they were left behind when the surrounding rock eroded away. Famous rock outcrops on Earth with a similar origin are called hoodoos. NASA’s Curiosity Rover continues to search for new signs of ancient water in Gale Crater on Mars, while also providing a geologic background important for future human exploration.

Tomorrow’s picture: city suns

Astronomy Picture of the Day

The Gamma Cygni Nebula
Image Credit & Copyright: Min Xie, Chen Wu, Yizhou Zhang, and Benchu Tang

Explanation: Supergiant star Gamma Cygni is at the center of the Northern Cross. Near the plane of our Milky Way galaxy, that famous asterism flies high in northern summer night skies in the constellation Cygnus the Swan. Known by the proper name Sadr, Gamma Cygni also lies just below center in this telescopic skyscape, with colors mapped from both broadband and narrowband image data. The field of view spans about 3 degrees (six Full Moons) on the sky and includes emission nebula IC 1318 and open star cluster NGC 6910. Filling the upper part of the frame and shaped like two glowing cosmic wings divided by a long dark dust lane, IC 1318’s popular name is understandably the Butterfly Nebula. Right of Gamma Cygni, are the young, still tightly grouped stars of NGC 6910. The distance to Gamma Cygni is around 560 parsecs or 1,800 light-years. Estimates for IC 1318 and NGC 6910 range from 2,000 to 5,000 light-years.

Tomorrow’s picture: don’t crash

Astronomy Picture of the Day

Good Morning Planets from Chile
Image Credit & Copyright: Elke Schulz (Daniel Verschatse Observatory)

Explanation: On June 15, innermost planet Mercury had wandered about as far from the Sun as it ever gets in planet Earth’s sky. Near the eastern horizon just before sunrise it stands over distant Andes mountain peaks in this predawn snapshot from the valley of Rio Hurtado in Chile. June’s other morning planets are arrayed above it, as all the naked-eye planets of the Solar System stretch in a line along the ecliptic in the single wide-field view. Tilted toward the north, the Solar System’s ecliptic plane arcs steeply through southern hemisphere skies. Northern hemisphere early morning risers will see the lineup of planets along the ecliptic at a shallower angle tilting toward the south. From both hemispheres June’s beautiful morning planetary display finds the visible planets in order of their increasing distance from the Sun.

Tomorrow’s picture: light-weekend

Astronomy Picture of the Day

Strawberry Supermoon from China
Image Credit & Copyright: Jeff Dai (TWAN)

Explanation: There are four Full Supermoons in 2022. Using the definition of a supermoon as a Full Moon near perigee, that is within at least 90% of its closest approach to Earth in a given orbit, the year’s Full Supermoon dates are May 16, June 14, July 13, and August 12. Full Moons near perigee really are the brightest and largest in planet Earth’s sky. But size and brightness differences between Full Moons are relatively small and an actual comparison with other Full Moons is difficult to make by eye alone. Two exposures are blended in this supermoon and sky view from June 14. That Full Moon was also known to northern hemisphere skygazers as the Strawberry moon. The consecutive short and long exposures allow familiar features on the fully sunlit lunar nearside to be seen in the same image as a faint lunar corona and an atmospheric cloudscape. They were captured in skies over Chongqing, China.

Tomorrow’s picture: planets in space