Galaxy Wars: M81 and M82

The two dominant galaxies near center are far far away, 12 million light-years distant toward the northern constellation of the Great Bear. On the right, with grand spiral arms and bright yellow core is spiral galaxy M81. Also known as Bode's galaxy, M81 spans some 100,000 light-years. On the left is cigar-shaped irregular galaxy M82. The pair have been locked in gravitational combat for a billion years. Gravity from each galaxy has profoundly affected the other during a series of cosmic close encounters. Their last go-round lasted about 100 million years and likely raised density waves rippling around M81, resulting in the richness of M81's spiral arms. M82 was left with violent star forming regions and colliding gas clouds so energetic that the galaxy glows in X-rays. In the next few billion years, their continuing gravitational encounters will result in a merger, and a single galaxy will remain. This extragalactic scenario also includes other members of the interacting M81 galaxy group with NGC 3077 below and right of the large spiral, and NGC 2976 at upper right in the frame. Captured under dark night skies in the Austrian Alps, the foreground of the wide-field image is filled with integrated flux nebulae. Those faint, dusty interstellar clouds reflect starlight above the plane of our own Milky Way galaxy.

from NASA https://ift.tt/dR8hEft

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The Pencil Nebula Supernova Shock Wave

This supernova shock wave plows through interstellar space at over 500,000 kilometers per hour. Near the middle and moving up in this sharply detailed color composite , thin, bright, braided filaments are actually long ripples in a cosmic sheet of glowing gas seen almost edge-on. Cataloged as NGC 2736 , its elongated appearance suggests its popular name, the Pencil Nebula . The Pencil Nebula is about 5 light-years long and 800 light-years away, but represents only a small part of the Vela supernova remnant . The Vela remnant itself is around 100 light-years in diameter, the expanding debris cloud of a star that was seen to explode about 11,000 years ago. Initially, the shock wave was moving at millions of kilometers per hour but has slowed considerably, sweeping up surrounding interstellar material. In the featured narrow-band, wide field image , red and blue colors track, primarily, the characteristic glows of ionized hydrogen and oxygen atoms , respectively. from NASA https...

This surprising sky has almost everything. First, slanting down from the upper left and far in the distance is the central band of our Milky Way Galaxy . More modestly, slanting down from the upper right and high in Earth's atmosphere is a bright meteor . The dim band of light across the central diagonal is zodiacal light : sunlight reflected from dust in the inner Solar System . The green glow on the far right is aurora high in Earth's atmosphere . The bright zigzagging bright line near the bottom is just a light that was held by the scene-planning astrophotographer . This " almost everything " sky was captured over rocks on Castle Hill , New Zealand late last month. The featured finished frame is a combination of 10 exposures all taken with the same camera and from the same location. But what about the astrophotographer himself? He's pictured too -- can you find him ? from NASA https://ift.tt/8TFhCw3

Lightning and Orion Beyond Uluru

What's happening behind Uluru? A United Nations World Heritage Site , Uluru is an extraordinary 350-meter high mountain in central Australia that rises sharply from nearly flat surroundings. Composed of sandstone , Uluru has slowly formed over the past 300 million years as softer rock eroded away. In the background of the featured image taken in mid-May, a raging thunderstorm is visible. Far behind both Uluru and the thunderstorm is a star-filled sky highlighted by the constellation of Orion. The Uluru region has been a home to humans for over 22,000 years. Local indigenous people have long noted that when the stars that compose the modern constellation of Orion first appear in the night sky, a hot season involving lightning storm s will soon be arriving. from NASA https://ift.tt/3uy2PLM

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