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Astronomy Picture of the Day

Comet Clark is near the Edge
Image Credit & Copyright: Raul Villaverde Fraile

Explanation: Sweeping through this stunning field of view, Comet 71P/Clark really is in the foreground of these cosmic clouds. The 2 panel telescopic mosaic is color enhanced and is about 5 degrees (10 full moons) across. It captures the faint comet’s position on the night of May 23/24 over 5 light-minutes from Earth, very near the line-of-sight to bright star Antares and the Rho Ophiuchi cloud complex. In the frame Antares, also known as Alpha Scorpii, is at bottom center surrounded by a dusty cosmic cloud reflecting the cool giant star’s yellowish light. Globular star cluster M4 shines just right of Antares, but M4 lies some 7,000 light-years away compared to Antares’ 500 light-year distance. Slightly closer than Antares, Rho Ophiuchi’s bluish starlight is reflected by the dust in molecular clouds toward the top. You can spot the small coma and short tail of the comet as a faint smudge near the center of the left edge of the frame. Just look for the comet’s striking greenish color, produced as diatomic carbon molecules fluoresce in sunlight.

Tomorrow’s picture: collapse on mars

Astronomy Picture of the Day

Spiral Galaxy NGC 6744
Image Credit & Copyright: Daniel Verschatse

Explanation: Big, 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 appearing as a faint, extended object in small telescopes. We see the disk of the nearby island universe tilted towards our line of sight. This remarkably distinct and detailed galaxy portrait covers an area about the angular size of the full moon. In it, the giant galaxy’s yellowish core is dominated by the light from old, cool stars. Beyond the core, spiral arms filled with young blue star clusters and pinkish star forming regions sweep past a smaller satellite galaxy at the lower left, reminiscent of the Milky Way’s satellite galaxy the Large Magellanic Cloud.

Tomorrow’s picture: colorful clouds + 1

Astronomy Picture of the Day

Star Cluster, Spiral Galaxy, Supernova
Image Credit & Copyright: Paolo Demaria

Explanation: A cosmic snapshot from May 19, this colorful telescopic field of view spans about 1 degree or 2 full moons on the sky. Spiky in appearance, foreground Milky Way stars are scattered toward the royal constellation Cepheus while stars of open cluster NGC 6939 gather about 5 thousand light-years in the distance near the top of the frame. Face-on spiral galaxy NGC 6946 is toward the lower left nearly 22 million light-years away. The helpful red lines identify recently discovered supernova SN 2017eaw, the death explosion of a massive star nestled in the galaxy’s bluish spiral arms. In fact in the last 100 years, 10 supernovae have been discovered in NGC 6946. By comparison, the average rate of supernovae in our Milky Way is about 1 every 100 years or so. Of course, NGC 6946 is also known as The Fireworks Galaxy.

Tomorrow’s picture: pixels in space

Astronomy Picture of the Day

Approaching Jupiter
Video Composition & Copyright: Peter Rosén et al.; Music: The Awakening by Clemens Ruh

Explanation: What would it look like to approach Jupiter? To help answer this, a team of 91 amateur astrophotographers took over 1,000 pictures of Jupiter from the Earth with the resulting images aligned and digitally merged into the featured time-lapse video. Image taking began in 2014 December and lasted just over three months. The resulting fictitious approach sequence has similarities to what was seen by NASA’s robotic Juno spacecraft as it first approached the Jovian world last July. The video begins with Jupiter appearing as a small orb near the image center. As Jupiter nears from below, the planet looms ever larger while the rotation of its cloud bands becomes apparent. Jupiter’s shrinking Great Red Spot rotates into view twice, at times showing unusual activity. Many white ovals are visible moving around the giant planet. The video ends as the imaginary spacecraft passes over Jupiter’s North Pole.

Tomorrow’s picture: galaxy needle

Astronomy Picture of the Day

In the Center of the Lagoon Nebula
Image Credit: Hubble, A. Caulet (ST-ECF, ESA), NASA

Explanation: The center of the Lagoon Nebula is a whirlwind of spectacular star formation. Visible on the lower left, at least two long funnel-shaped clouds, each roughly half a light-year long, have been formed by extreme stellar winds and intense energetic starlight. The tremendously bright nearby star, Hershel 36, lights the area. Vast walls of dust hide and redden other hot young stars. As energy from these stars pours into the cool dust and gas, large temperature differences in adjoining regions can be created generating shearing winds which may cause the funnels. This picture, spanning about 5 light years, was taken in 1995 by the orbiting Hubble Space Telescope. The Lagoon Nebula, also known as M8, lies about 5000 light years distant toward the constellation of Sagittarius.

  Tomorrow’s picture: canyon sky triangle

Astronomy Picture of the Day

Simeis 147: Supernova Remnant
Image Credit & Copyright: Daniel López (El Cielo de Canarias) / IAC

Explanation: It’s easy to get lost following intricate filaments in this detailed image of faint supernova remnant Simeis 147. Also cataloged as Sharpless 2-240 it goes by the popular nickname, the Spaghetti Nebula. Seen toward the boundary of the constellations Taurus and Auriga, it covers nearly 3 degrees or 6 full moons on the sky. That’s about 150 light-years at the stellar debris cloud’s estimated distance of 3,000 light-years. This composite includes image data taken through narrow-band filters, enhancing the reddish emission from ionized hydrogen atoms to trace the shocked, glowing gas. The supernova remnant has an estimated age of about 40,000 years, meaning light from the massive stellar explosion first reached Earth 40,000 years ago. But the expanding remnant is not the only aftermath. The cosmic catastrophe also left behind a spinning neutron star or pulsar, all that remains of the original star’s core.

Tomorrow’s picture: pixels in space

Astronomy Picture of the Day

Galaxy Group Hickson 90
Image Credit: NASA; ESA, Hubble Legacy Archive; Processing: Oliver Czernetz

Explanation: Scanning the skies for galaxies, Canadian astronomer Paul Hickson and colleagues identified some 100 compact groups of galaxies, now appropriately called Hickson Compact Groups (HCGs). This sharp Hubble image shows one such galaxy group, HCG 90, in startling detail. Three galaxies — two visible here — are revealed to be strongly interacting: a dusty spiral galaxy stretched and distorted in the image center, and two large elliptical galaxies. The close encounter will trigger furious star formation. On a cosmic timescale, the gravitational tug of war will eventually result in the merger of the trio into a large single galaxy. The merger process is now understood to be a normal part of the evolution of galaxies, including our own Milky Way. HCG 90 lies about 100 million light-years away toward the constellation of the Southern Fish (Piscis Austrinus). This Hubble view spans about 40,000 light-years at that estimated distance. Of course, Hickson Compact Groups also make for rewarding viewing for Earth-bound astronomers with more modest sized telescopes.

Tomorrow’s picture: old boom field