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Solar filters for observing the Sun

Thursday, January 20th 2022 03:19 PM

  Limb darkening is evident in this image of the Sun viewed through a simple Coronado Personal Solar Telescope (PST). The PST is a Hydrogen-alpha-filtered refractor with a 40mm aperture and a 400mm focal length that can only be used for solar observing. For many, astronomy is a late-night pursuit. We anxiously wait for Sol to set and twilight to fade before we begin to enjoy the sky. But by doing so, we are missing an amazing matinee every day — one performed by the Sun. Our star is the perfect target for observers. No chart is needed to find it. You can’t beat it for convenience. And light pollution doesn’t even enter into the equation. With the Sun, there’s no need to pull an all-nighter. Best of all, it is always changing. While most distant deep-sky objects appear static over the course of a human lifespan, the Sun changes every day. That makes it exciting to watch! But in order to enjoy the show, you need to come prepared. The Sun is the only celes...

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Image of the Day: Peering Through a Window to the World

Thursday, January 20th 2022 09:12 AM

  In this image from Jan. 9, 2022, NASA astronaut Kayla Barron peered out from a window inside the cupola, the International Space Station's "window to the world." Prominent station components in this photograph include the Kibo laboratory module and its external pallet, the Japanese robotic arm, and the Leonardo Permanent Multipurpose Module.   Image Credit: NASA  

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Grab-and-go astrophotography

Wednesday, January 19th 2022 10:15 AM

  This bicolor image of the Rosette Nebula (NGC 2237-9) using Astrodon Hydrogen-alpha and Oxygen-III filters required six hours of exposures through a Starlight Xpress H694 monochrome camera attached to a William Optics GT81 refractor on an iOptron CEM60 mount. With more of us living in cities and urban environments, the problem of light pollution is all too familiar. Even those lucky enough to live outside large metropolises don’t escape untouched, because the sky near the horizon is often lost to sky glow. This leaves astroimagers with a choice to make: Invest in a fixed setup with narrowband or light pollution filters, or make the best of a lightweight, portable setup and head to dark-sky sites. In my case, the choice was made for me. I live in the center of a city, so a permanent setup was neither a viable nor secure option.   The author stands next to one of his portable astroimaging setups. But how far can one go in this hobby with a kit light enough to be t...

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Image of the Day: Drilling Holes on the Red Planet

Tuesday, January 18th 2022 09:15 AM

  This image shows the Highfield drill hole, on Vera Rubin Ridge in Gale crater on Mars, made by NASA’s Curiosity rover. Just recently, scientists announced that an analysis of rock samples collected by the rover were enriched in carbon 12, a type of carbon that on Earth is associated with biological processes. While the finding is intriguing, it doesn’t necessarily point to ancient life on Mars, as scientists have not yet found conclusive supporting evidence of ancient or current biology there, such as sedimentary rock formations produced by ancient bacteria, or a diversity of complex organic molecules formed by life. The image of this drill hole was taken by the Mars Hand Lens Imager of the Curiosity rover on the 2,247th Martian day, or sol, of the mission.   Image credits: NASA/Caltech-JPL/MSSS  

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The Sky This Week: The morning star reappears

Friday, January 14th 2022 09:57 AM

Friday, January 14   The Circlet and the carbon star: A bright Moon floats inside the Circlet of Pisces, which includes the red carbon star 19 Piscium, visible as the red point below the Moon. The Moon reaches apogee, the farthest point from Earth in its orbit, at 4:26 A.M. EST. At that time, our satellite will be 252,155 miles (405,804 km) away. With the bright Moon in Taurus tonight, let’s cast our gaze across the sky to Pisces to discover one of the sky’s reddest rubies. 19 Piscium, also called TX Piscium, is a deep red carbon star. This means it’s in the later stages of its life and has puffed up into a cool red giant. That alone will make a star appear redder, but carbon stars go one step further: These stars have abundant carbon in their atmosphere, which readily scatters blue and green wavelengths of light so only the red can shine through. Thus, carbon stars appear particularly red. To find 19 Psc, step outside early in the evening, before Pisces has...

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Unveiling the clouds of Venus

Tuesday, December 28th 2021 11:40 AM

  The dense clouds of Venus are on full display in this ultraviolet image taken by the Pioneer Venus Orbiter on Feb. 5, 1979. Venus’ clouds have long been known to absorb ultraviolet radiation, but exactly how and why remains a mystery. As brilliant and splendid as Venus is to the naked eye, the world often ranks as one of astronomy’s great telescopic disappointments. Apart from its evolving phase and its dazzling, ubiquitous cloud deck, the casual observer can see very little detail. As brilliant and splendid as Venus is to the naked eye, the world often ranks as one of astronomy’s great telescopic disappointments. Apart from its evolving phase and its dazzling, ubiquitous cloud deck, the casual observer can see very little detail. The famed English amateur astronomer William F. Denning wrote in Telescopic Work for Starlight Evenings (1891): “When the telescope is directed to Venus it must be admitted that the result hardly justifies the anticipation. O...

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Discover the sky’s best double stars

Thursday, December 23rd 2021 10:05 AM

  The Big Dipper in Ursa Major houses a famous double star that ancient Arabic texts refer to as a visual test. Just at the kink in the Dipper’s handle is bright Mizar, with dimmer Alcor 12' to its east-northeast (upper left in this image). Viewing double stars is a popular activity at star parties. The presenter will usually point out Mizar and its dimmer companion, Alcor, in the bend of the Big Dipper’s handle; or, in summer, telescopes are often turned to Albireo in Cygnus, to everyone’s delight. But double stars are often neglected by today’s serious amateur observers, who are more interested in deep-sky objects. It’s a shame, because not only are double stars beautiful, but they are also a challenge by which to measure the skill of the observer and the quality of their telescope. Double stars were once the focus of both professional and amateur observers alike, and they have played an important role in our understanding of gravity and of the g...

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Snapshot: Milky Way stars photobomb distant galaxy

Tuesday, December 21st 2021 09:37 AM

  Located some 230 million light-years away in the constellation Aquila the Eagle is the majestic galaxy UGC 11537. Because this distant, tightly wound spiral appears so near the plane of our own Milky Way, two foreground stars are prominently photobombing UGC 11537 in this Hubble Space Telescope image. Each of these foreground stars displays a strong starburst effect, which is an optical artifact that results from starlight hitting Hubble’s secondary mirror, producing so-called diffraction spikes.   Three examples of image artifacts appearing in NASA images. LEFT: Venus appears like a butterfly of light in this STEREO coronagraph image due to the way the instrument bent its incoming light. MIDDLE: Venus is again affected by an artifact, this time appearing to streak to the sides caused by an excess signal. RIGHT: NASA's STEREO coronagraph caught this image of a highly energetic particle passing through the instrument. But starbursts aren’t the only example o...

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  These blueprints of the James Webb Space Telescope were created as a prop for a video series, but since it was requested, we are offering them as a download! (Look close and you'll notice some of the smaller text is Latin!) Webb is targeted to launch at 7:20 a.m. EST Friday, Dec. 24, on an Arianespace Ariane 5 rocket from Europe’s Spaceport in Kourou, French Guiana, on the northeastern coast of South America.   Image Credit: NASA

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The Sky This Week: Winter officially begins

Friday, December 17th 2021 09:26 AM

  Northern lights: Jupiter and Venus set amid the northern lights as seen from Ruka, Finland, in early 2012.   Friday, December 17 2021’s best comet, C/2021 A1 (Leonard), floats just 5° below Venus in the evening sky tonight. Depending on the Leonard’s current magnitude, it may be just visible to the naked eye in the falling twilight. To catch the stunning scene, turn southwest after sunset. You absolutely won’t be able to miss Venus’ magnitude –4.9 glow, still 20° above the horizon as the Sun disappears. Let the sky begin to darken and your eyes adjust with it as you start scanning for Leonard’s faint, fuzzy coma. Binoculars will greatly aid your search, but make sure the Sun is completely gone from the sky before pulling them out. If you’re an astrophotographer, you won’t want to miss this picturesque view, and photographs will certainly bring out Leonard’s still-bright dust tail and enhance the amount of i...

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