A spitting image of a Tie Fighter crossing the moon, spectacular Nebulas pump light into the universe and a stunning rift in the Milky Way are among this week's pictures from NASA's Astronomy archive.apod.nasa.gov
Why is there a bridge between these two spiral galaxies? Made of gas and stars, the bridge provides strong evidence that these two immense star systems have passed close to each other and experienced violent tides induced by mutual gravity. Known together as Arp 240 but individually as NGC 5257 and NGC 5258, computer modelling and the ages of star clusters indicate that the two galaxies completed a first passage near each other only about 250 million years ago. Gravitational tides not only pulled away matter, they compress gas and so caused star formation in both galaxies and the unusual bridge. Galactic mergers are thought to be common, with Arp 240 representing a snapshot of a brief stage in this inevitable process. The Arp 240 pair are about 300 million light-years distant and can be seen with a small telescope toward the constellation of Virgo. Repeated close passages should ultimately result in a merger and with the emergence of a single combined galaxy.
Photography: NASA, ESA, Hubble Space Telescope; Processing & Copyright: Chris Kotsiopoulos
What are those specks in front of the Moon? They are silhouettes of the International Space Station (ISS). Using careful planning and split-second timing, a meticulous lunar photographer captured ten images of the ISS passing in front of last month's full moon. But this wasn't just any full moon -- this was the first of the three consecutive 2016 supermoons. A supermoon is a full moon that appears a few percent larger and brighter than most other full moons. The featured image sequence was captured near Dallas, Texas. Occurring today is the second supermoon of this series, a full moon that is the biggest and brightest not only of the year, but of any year since 1948. To see today's super-supermoon yourself, just go outside at night and look up. The third supermoon of this year's series will occur in mid-December.
Photography: Kris Smith
Is the heart and soul of our Galaxy located in Cassiopeia? Possibly not, but that is where two bright emission nebulas nicknamed Heart and Soul can be found. The Heart Nebula, officially dubbed IC 1805 and visible in the featured image on the right, has a shape reminiscent of a classical heart symbol. Both nebulas shine brightly in the red light of energized hydrogen. Several young open clusters of stars populate the image and are visible here in blue, including the nebula centers. Light takes about 6,000 years to reach us from these nebulas, which together span roughly 300 light years. Studies of stars and clusters like those found in the Heart and Soul Nebulas have focused on how massive stars form and how they affect their environment.
Photography: David Lindemann
Hot, young stars and cosmic pillars of gas and dust seem to crowd into NGC 7822. At the edge of a giant molecular cloud toward the northern constellation Cepheus, the glowing star forming region lies about 3,000 light-years away. Within the nebula, bright edges and dark shapes stand out in this colorful skyscape. The image includes data from narrowband filters, mapping emission from atomic oxygen, hydrogen, and sulfur into blue, green, and red hues. The emission line and color combination has become well-known as the Hubble palette. The atomic emission is powered by energetic radiation from the central hot stars. Their powerful winds and radiation sculpt and erode the denser pillar shapes and clear out a characteristic cavity light-years across the center of the natal cloud. Stars could still be forming inside the pillars by gravitational collapse but as the pillars are eroded away, any forming stars will ultimately be cutoff from their reservoir of star stuff. This field of view spans over 40 light-years at the estimated distance of NGC 7822.
Photography: Steve Cannistra (StarryWonders)
Over 100 telescopic image panels in this stunning vertical mosaic span about 50 degrees across the night sky. They follow part of the Great Rift, the dark river of dust and molecular gas that stretches along the plane of our Milky Way Galaxy. Start at top center and you can follow the galactic equator down through brighter stars in constellations Aquila, Serpens Cauda, and Scutum. At the bottom is Sagittarius near the center of the Milky Way. Along the way you'll encounter many obscuring dark nebulae hundreds of light-years distant flanked by bands of Milky Way starlight, and the telltale reddish glow of starforming regions. Notable Messier objects include The Eagle (M16) and Omega (M17) nebulae, the Sagittarius Star Cloud (M24), the beautiful Trifid (M20) and the deep Lagoon (M8).
Photography: Rogelio Bernal Andreo (Deep Sky Colors)