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Image of the Day: Eagle, Omega Nebula, Trifid, and Lagoon: Four Famous Nebulae

Thursday, December 2nd 2021 05:25 PM

  Nebula [ neb-yuh-luh ]: star-forming cloud of gas and dust. Noun, plural neb·u·lae [neb-yuh-lee, -lahy] These four nebulae are known for their breathtaking beauty: the Eagle Nebula (which contains the Pillars of Creation), the Omega Nebula, the Trifid Nebula, and the Lagoon Nebula. In the 1950s, a team of astronomers made rough distance measurements to some of the stars in these nebulae and were able to infer the existence of the Sagittarius Arm. Their work provided some of the first evidence of our galaxy's spiral structure. In a new study, astronomers have shown that these nebulae are part of a substructure within the arm that is angled differently from the rest of the arm. A key property of spiral arms is how tightly they wind around a galaxy. This characteristic is measured by the arm's pitch angle. A circle has a pitch angle of 0 degrees, and as the spiral becomes more open, the pitch angle increases. Most models of the Milky Way suggest that the Sagittariu...

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Sky This Month: December 2021

Wednesday, December 1st 2021 05:25 PM

  Venus reaches greatest brilliancy early this month as an evening star. The planet reached the same magnitude in this 2018 shot as a morning star. December’s early-evening sky offers a slew of planetary views, beginning with Venus, Saturn, and Jupiter — all on show soon after sunset. Capture the top features of the solar system in one evening by spotting the changing phase of Venus; the spectacular rings of Saturn; and the remarkably dynamic jovian atmosphere, its Great Red Spot, and Jupiter’s four bright moons. The first planet to appear after sunset is Venus, hanging low in the southwest. It reaches greatest brilliancy Dec. 4, when it shines at magnitude –4.9, easily piercing the bright twilight. This unmistakable brilliant jewel lies in eastern Sagittarius, featuring in all evening photographic compositions of the broad Milky Way. A waxing crescent Moon, complete with earthshine, joins Venus Dec. 6, standing less than 3° away. As Venus slowly ap...

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Image of the Day: Dragons-Eye View

Wednesday, December 1st 2021 12:31 AM

  As the Crew-2 mission departed the International Space Station aboard SpaceX Crew Dragon Endeavour, the crew snapped this image of the station during a flyaround of the orbiting lab that took place following undocking from the Harmony module’s space-facing port on Nov. 8, 2021. NASA’s SpaceX Crew-2 mission was the second operational mission of the SpaceX Crew Dragon spacecraft and Falcon 9 rocket to the International Space Station as part of the agency’s Commercial Crew Program, which has worked with the U.S. aerospace industry to launch astronauts on American rockets and spacecraft from American soil to the space station.   Image Credit: NASA

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The Sky This Week: Last Quarter Moon in the morning

Monday, November 29th 2021 05:28 PM

  Friday, November 26   The Hyades cluster: The stars of the Hyades lay scattered across Taurus’ face, along with the bright red star Aldebaran. Dwarf planet 1 Ceres is at opposition tonight at 11 P.M. EST. It’s visible all evening, located amid the stars of the Hyades, situated on the nose of Taurus the Bull. His bright red eye, Aldebaran, can guide you: Ceres sits 5° due west of this 1st-magnitude star. The dwarf planet glows at magnitude 7.7, reachable with binoculars or a small telescope. But while you’re searching out this single point of light, take some time to enjoy its surroundings as well. The Hyades is a young cluster about 150 light-years away and its stars are about 625 million years old. Although Aldebaran sits near the loosely scattered Hyades, it is not part of the cluster. Aldebaran is an aging red giant star nearly 70 light-years away. It’s the 14th-brightest star in the sky and stretches out to some 43 times the distance of...

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Image of the Day: Hubble Witnesses Shock Wave of Colliding Gases in Running Man Nebula

Wednesday, November 24th 2021 05:16 PM

  Mounded, luminous clouds of gas and dust glow in this Hubble image of a Herbig-Haro object known as HH 45. Herbig-Haro objects are a rarely seen type of nebula that occurs when hot gas ejected by a newborn star collides with the gas and dust around it at hundreds of miles per second, creating bright shock waves. In this image, blue indicates ionized oxygen (O II) and purple shows ionized magnesium (Mg II). Researchers were particularly interested in these elements because they can be used to identify shocks and ionization fronts. This object is located in the nebula NGC 1977, which itself is part of a complex of three nebulae called The Running Man. NGC 1977 – like its companions NGC 1975 and NGC 1973 – is a reflection nebula, which means that it doesn’t emit light on its own, but reflects light from nearby stars, like a streetlight illuminating fog. Hubble observed this region to look for stellar jets and planet-forming disks around young stars, and examine...

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Image of the Day: Hubble Spots Swirls of Dust in the Flame Nebula

Monday, November 22nd 2021 05:26 PM

  The Flame Nebula, also called NGC 2024, is a large star-forming region in the constellation Orion that lies about 1,400 light-years from Earth. It’s a portion of the Orion Molecular Cloud Complex, which includes such famous nebulae as the Horsehead Nebula and Orion Nebula. This image focuses on the dark, dusty heart of the nebula, where a star cluster resides, mostly hidden from view. Nearby (but not visible in this image) is the bright star Alnitak, the easternmost star in the Belt of Orion. Radiation from Alnitak ionizes the Flame Nebula’s hydrogen gas. As the gas begins to cool from its higher-energy state to a lower-energy state, it emits energy in the form of light, causing the visible glow behind the swirled wisps of dust. Researchers have used Hubble to measure the mass of stars in the cluster as they search for brown dwarfs, a type of dim object that’s too hot and massive to be classified as a planet but also too small and cool to shine like a star....

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The Sky This Week: Venus blazes bright

Friday, November 19th 2021 05:42 PM

  Turkey time: The Orion Nebula (M42) is a famous, oft-observed target. Some might say it even looks like a turkey. What do you think?   Friday, November 19 Early risers this morning can catch the longest partial lunar eclipse of the century, during which some 98 percent of our satellite slides into Earth’s shadow. The effect is a deep red-colored Moon. If you didn’t get a chance to watch, don’t worry — astronomy livestreamer David Brewer filmed the entire event from Denver, Colorado.   Full Moon occurs this morning at 3:57 A.M. EST. November’s Full Moon is also called the Beaver Moon. If you’re more of an evening observer, you’re in luck: The sky has another show in store for us tonight, this time as a brilliant planet Venus sits a half-Moon’s width from 2nd-magnitude Nunki in Sagittarius. Look south just after sunset to find a three-planet tableau, consisting of Venus farthest west, then Saturn 26° to its east...

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Catch this month's lunar eclipse, the longest of the century

Thursday, November 18th 2021 05:18 PM

  The Moon moves through Earth’s umbra — from right (west) to left (east) — in this composite assembled from multiple exposures taken during the Jan. 20, 2019, total lunar eclipse. Although this month’s event will not be a total lunar eclipse, at 97 percent coverage, it will still be a stunning sight. On Friday, Nov. 19, the Sun, Earth, and the Moon (in that order) will line up and most of Moon will trek through Earth’s umbra, the darkest part of its shadow. Although this won’t be a total lunar eclipse, it’ll be darn close. At mid-eclipse, 97 percent of our only natural satellite will be covered by Earth’s umbra. Observers with clear skies should be able to spot nearly all the effects that are visible during a total lunar eclipse. This wouldn’t be the case if it were a partial solar eclipse (with 3 percent of the Sun’s face uncovered, you would miss out on Baily’s beads, diamond rings, and the solar corona). In o...

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Image of the Day: Hubble Spies Newly Forming Star Incubating in IC 2631

Wednesday, November 17th 2021 05:20 PM

Image of the Day: Hubble Spies Newly Forming Star Incubating in IC 2631   Stars are born from clouds of gas and dust that collapse under their own gravitational attraction. As the cloud collapses, a dense, hot core forms and begins gathering dust and gas, creating an object called a “protostar.” This Hubble infrared image captures a protostar designated J1672835.29-763111.64 in the reflection nebula IC 2631, part of the Chamaeleon star-forming region in the southern constellation Chamaeleon. Protostars shine with the heat energy released by clouds contracting around them and the accumulation of material from the nearby gas and dust. Eventually enough material collects, and the core of a protostar becomes hot and dense enough for nuclear fusion to begin, and the transformation into a star is complete. The leftover gas and dust can become planets, asteroids, comets, or remain as dust. This image is part of a Hubble survey targeting 312 protostars within molecular clo...

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Snapshot: Hubble spots a mysterious superbubble

Tuesday, November 16th 2021 05:33 PM

  Lurking within the Large Magellanic Cloud, approximately 170,000 light-years away, is N44. This cosmic gem is notable not for the nebula’s complexity, massive stars, or glowing hydrogen gas, but for its hollowed-out core. Some 250 light-years wide, the hole, called a superbubble, is a cosmic enigma. One theory for the superbubble’s presence is that stellar winds from massive stars at its core may have blown away the gas. But this doesn’t line up with the velocity of the winds measured inside its boundaries. Another theory points to the population of massive stars within the nebula itself. These stars would produce catastrophic supernovae, their remnant shells expanding as they age. Therefore, a series of supernovae may have carved out the gaping wound within N44. However, only one supernova remnant has been identified inside the superbubble so far. About 1,000 light-years across, N44 glows thanks to its ionized gas, as seen in the Hubble image above. The bri...

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