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Astronomy Picture of the Day

Veil Nebula: Wisps of an Exploded Star
Image Credit: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)

Explanation: Wisps like this are all that remain visible of a Milky Way star. About 7,000 years ago that star exploded in a supernova leaving the Veil Nebula. At the time, the expanding cloud was likely as bright as a crescent Moon, remaining visible for weeks to people living at the dawn of recorded history. Today, the resulting supernova remnant, also known as the Cygnus Loop, has faded and is now visible only through a small telescope directed toward the constellation of the Swan (Cygnus). The remaining Veil Nebula is physically huge, however, and even though it lies about 1,400 light-years distant, it covers over five times the size of the full Moon. The featured picture is a Hubble Space Telescope mosaic of six images together covering a span of only about two light years, a small part of the expansive supernova remnant. In images of the complete Veil Nebula, even studious readers might not be able to identify the featured filaments.

Tomorrow’s picture: the big corona

Astronomy Picture of the Day

Orion above Easter Island
Image Credit & Copyright: Yuri Beletsky (Carnegie Las Campanas Observatory, TWAN)

Explanation: Why were the statues on Easter Island built? No one is sure. What is sure is that over 800 large stone statues exist there. The Easter Island statues, stand, on the average, over twice as tall as a person and have over 200 times as much mass. Few specifics are known about the history or meaning of the unusual rock sculptures, but many believe that they were created about 700 years ago in the images of local leaders of a lost civilization. Featured here, one of the ancient Moai sculptures was imaged in 2016 before the constellation of Orion, including the famous line of three belt stars and brilliant stars Betelgeuse (far left in red) and Rigel (upper center). The stone giant appears, however, to be inspecting the brightest star in the night sky (far right): Sirius.

Tomorrow’s picture: wisps of the veil

Astronomy Picture of the Day

Bright Spiral Galaxy M81
Image Credit: Subaru Telescope (NAOJ), Hubble Space Telescope;
Processing & Copyright: Roberto Colombari & Robert Gendler

Explanation: One of the brightest galaxies in planet Earth’s sky is similar in size to our Milky Way Galaxy: big, beautiful M81. This grand spiral galaxy can be found toward the northern constellation of the Great Bear (Ursa Major). This superbly detailed view reveals M81’s bright yellow nucleus, blue spiral arms, and sweeping cosmic dust lanes with a scale comparable to the Milky Way. Hinting at a disorderly past, a remarkable dust lane actually runs straight through the disk, to the left of the galactic center, contrary to M81‘s other prominent spiral features. The errant dust lane may be the lingering result of a close encounter between M81 and its smaller companion galaxy, M82. Scrutiny of variable stars in M81 has yielded one of the best determined distances for an external galaxy — 11.8 million light-years.

Tomorrow’s picture: easter orion

Astronomy Picture of the Day

Cassini’s Final Image
Image Credit: NASA, JPL-Caltech, Space Science Institute

Explanation: As planned, the Cassini spacecraft impacted the upper atmosphere of Saturn on September 15, after a 13 year long exploration of the Saturnian System. With spacecraft thrusters firing until the end, its atmospheric entry followed an unprecedented series of 22 Grand Finale dives between Saturn and rings. Cassini’s final signal took 83 minutes to reach planet Earth and the Deep Space Network antenna complex in Canberra Australia where loss of contact with the spacecraft was recorded at 11:55 UT. For the spacecraft, Saturn was bright and the Sun was overhead as it plowed into the gas giant planet’s swirling cloud tops at about 70,000 miles (113,000 kilometers) per hour. But Cassini’s final image shows the impact site hours earlier and still on the planet’s night side, the cloud tops illuminated by ringlight, sunlight reflected from Saturn’s rings.

Tomorrow’s picture: big bright galaxy

Astronomy Picture of the Day

100 Steps Forward
Image Credit & Copyright: Camilo Jaramillo

Explanation: A beautiful conjunction of Venus and Moon, human, sand, and Milky Way is depicted in this night skyscape from planet Earth. The scene is a panorama of 6 photos taken in a moment near the end of a journey. In the foreground, footsteps along the wind-rippled dunes are close to the Huacachina oasis in the southwestern desert of Peru. An engaging perspective on the world at night, the stunning final image was also chosen as a winner in The World at Night’s 2017 International Earth and Sky Photo Contest.

Tomorrow’s picture: light-weekend

Astronomy Picture of the Day

Flare Well AR2673
Image Credit: NASA, SDO, GSFC

Explanation: Almost out of view from our fair planet, rotating around the Sun’s western edge giant active region AR2673 lashed out with another intense solar flare followed by a large coronal mass ejection on September 10. The flare itself is seen here at the right in an extreme ultraviolet image from the sun-staring Solar Dynamics Observatory. This intense flare was the fourth X-class flare from AR2673 this month. The active region’s most recent associated coronal mass ejection collided with Earth’s magnetosphere 2 days later. Say farewell to the mighty AR2673, for now. For the next two weeks, the powerful sunspot group will be on the Sun’s far side.

Tomorrow’s picture: 100 steps forward

Astronomy Picture of the Day

NGC 6334: The Cat’s Paw Nebula
Image Credit & Copyright: George Varouhakis

Explanation: Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat’s Paw Nebula visible in Scorpius. At 5,500 light years distant, Cat’s Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms. Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured here is a deep field image of the Cat’s Paw Nebula in light emitted by hydrogen, oxygen, and sulfur.

Tomorrow’s picture: open space