Archives de catégorie : Picture

The Fainting of Betelgeuse

Begirt with many a blazing star, Orion the Hunter is one of the most recognizable constellations. In this night skyscape the Hunter’s stars rise in the northern hemisphere’s winter sky on December 30, 2019, tangled in bare trees near Newnan, Georgia, USA. Red super giant star Betelgeuse stands out in yellowish hues at Orion’s shoulder left of center, but it no longer so strongly rivals the blue supergiant star Rigel at the Hunter’s foot. In fact, skygazers around planet Earth can see a strikingly fainter Betelgeuse now, its brightness fading by more than half in the final months of 2019. Betelgeuse has long been known to be a variable star, changing its brightness in multiple cycles with approximate short and long term periods of hundreds of days to many years. The star is now close to its faintest since photometric measurements in 1926/27, likely due in part to a near coincidence in the minimum of short and long term cycles. Betelgeuse is also recognized as a nearby red supergiant star that will end its life in a core collapse supernova explosion sometime in the next 1,000 years, though that cosmic cataclysm will take place a safe 700 light-years or so from our fair planet. via NASA https://ift.tt/2SKKJpZ

Betelgeuse Imagined

Why is Betelgeuse fading? No one knows. Betelgeuse, one of the brightest and most recognized stars in the night sky, is only half as bright as it used to be only five months ago. Such variability is likely just normal behavior for this famously variable supergiant, but the recent dimming has rekindled discussion on how long it may be before Betelgeuse does go supernova. Known for its red color, Betelgeuse is one of the few stars to be resolved by modern telescopes, although only barely. The featured artist’s illustration imagines how Betelgeuse might look up close. Betelgeuse is thought to have a complex and tumultuous surface that frequently throws impressive flares. Were it to replace the Sun (not recommended), its surface would extend out near the orbit of Jupiter, while gas plumes would bubble out past Neptune. Since Betelgeuse is about 700 light years away, its eventual supernova will not endanger life on Earth even though its brightness may rival that of a full Moon. Astronomers — both amateur and professional — will surely continue to monitor Betelgeuse as this new decade unfolds. via NASA https://ift.tt/2SHw3Yt

Cassini Spacecraft Crosses Saturns Ring Plane

If this is Saturn, where are the rings? When Saturn’s « appendages » disappeared in 1612, Galileo did not understand why. Later that century, it became understood that Saturn’s unusual protrusions were rings and that when the Earth crosses the ring plane, the edge-on rings will appear to disappear. This is because Saturn’s rings are confined to a plane many times thinner, in proportion, than a razor blade. In modern times, the robot Cassini spacecraft orbiting Saturn frequently crossed Saturn’s ring plane during its mission to Saturn, from 2004 to 2017. A series of plane crossing images from 2005 February was dug out of the vast online Cassini raw image archive by interested Spanish amateur Fernando Garcia Navarro. Pictured here, digitally cropped and set in representative colors, is the striking result. Saturn’s thin ring plane appears in blue, bands and clouds in Saturn’s upper atmosphere appear in gold. Details of Saturn’s rings can be seen in the high dark shadows across the top of this image, taken back in 2005. The moons Dione and Enceladus appear as bumps in the rings. via NASA https://ift.tt/39qKEOb

A Distorted Sunrise Eclipse

Yes, but have you ever seen a sunrise like this? Here, after initial cloudiness, the Sun appeared to rise in two pieces and during partial eclipse, causing the photographer to describe it as the most stunning sunrise of his life. The dark circle near the top of the atmospherically-reddened Sun is the Moon — but so is the dark peak just below it. This is because along the way, the Earth’s atmosphere had an inversion layer of unusually warm air which acted like a gigantic lens and created a second image. For a normal sunrise or sunset, this rare phenomenon of atmospheric optics is known as the Etrucan vase effect. The featured picture was captured two mornings ago from Al Wakrah, Qatar. Some observers in a narrow band of Earth to the east were able to see a full annular solar eclipse — where the Moon appears completely surrounded by the background Sun in a ring of fire. The next solar eclipse, also an annular eclipse, will occur in 2020 June. via NASA https://ift.tt/362kwH2

A Partial Solar Eclipse Sequence Reflected

What’s happened to the Sun? Yesterday, if you were in the right place at the right time, you could see the Sun rise partially eclipsed by the Moon. The unusual sight was captured in dramatic fashion in the featured image not only directly, in a sequence of six images, but also in reflection from Soltan Salt Lake in Iran. The almost-white Sun appears dimmer and redder near the horizon primarily because Earth’s atmosphere preferentially scatters away more blue light. Yesterday’s partial solar eclipse appeared in the sky over much of Asia and Australia, but those with a clear enough sky in a thin band across the Earth’s surface were treated to a more complete annular solar eclipse — where the Moon appears completely surrounded by the Sun in what is known as a ring of fire. The next annular solar eclipse will occur in 2020 June. via NASA https://ift.tt/2EVjMrh

The Northern Winter Hexagon

December’s New Moon brought a solar eclipse to some for the holiday season. It also gave beautiful dark night skies to skygazers around the globe, like this moonless northern winter night. In the scene, bright stars of the Winter Hexagon along the Milky Way are rising. Cosy mountain cabins in the snowy foreground are near the village of Oravska Lesna, Slovakia. The shining celestial beacons marking the well-known asterism are Aldebaran, Capella, Pollux (and Castor), Procyon, Rigel, and Sirius. This winter nightscape also reveals faint nebulae in Orion, and the lovely Pleiades star cluster. Slide your cursor over the image to trace the winter hexagon, or just follow this link. via NASA https://ift.tt/2SscnYG

An Annular Solar Eclipse over New Mexico

What is this person doing? In 2012 an annular eclipse of the Sun was visible over a narrow path that crossed the northern Pacific Ocean and several western US states. In an annular solar eclipse, the Moon is too far from the Earth to block out the entire Sun, leaving the Sun peeking out over the Moon’s disk in a ring of fire. To capture this unusual solar event, an industrious photographer drove from Arizona to New Mexico to find just the right vista. After setting up and just as the eclipsed Sun was setting over a ridge about 0.5 kilometers away, a person unknowingly walked right into the shot. Although grateful for the unexpected human element, the photographer never learned the identity of the silhouetted interloper. It appears likely, though, that the person is holding a circular device that would enable them to get their own view of the eclipse. The shot was taken at sunset on 2012 May 20 at 7:36 pm local time from a park near Albuquerque, New Mexico, USA. Tomorrow another annular solar eclipse will become visible, this time along a thin path starting in Saudi Arabia and going through southern India, Singapore, and Guam. However, almost all of Asia with a clear sky will be able to see, tomorrow, at the least, a partial solar eclipse. via NASA https://ift.tt/2QfdA2N

A Northern Winter Sky Panorama

What stars shine in Earth’s northern hemisphere during winter? The featured image highlights a number of bright stars visible earlier this month. The image is a 360-degree horizontal-composite panorama of 66 vertical frames taken consecutively with the same camera and from the same location at about 2:30 am. Famous stars visible in the picture include Castor & Pollux toward the southeast on the left, Sirius just over the horizon toward the south, Capella just over the arch of the Milky Way Galaxy toward the west, and Polaris toward the north on the right. Captured by coincidence is a meteor on the far left. In the foreground is the Museum of the Orava Village in Zuberec, Slovakia. This village recreates rural life in the region hundreds of years ago, while the image captures a timeless sky surely familar to village residents, a sky also shared with northern residents around the world. via NASA https://ift.tt/2MpqrOH

Places for OSIRIS REx to Touch Asteroid Bennu

Where is the best place to collect a surface sample from asteroid Bennu? Launched in 2016, NASA sent the robotic Origins, Spectral Interpretation, Resource Identification, Security, Regolith Explorer (OSIRIS-REx) to investigate the 500-meter-across asteroid 101955 Bennu. After mapping the near-Earth asteroid’s dark surface, OSIRIS-REx will next touch Bennu’s surface in 2020 August to collect a surface sample. The featured 23-second time-lapse video shows four candidate locations for the touch, from which NASA chose just one earlier this month. NASA chose the Nightingale near Bennu’s northern hemisphere as the primary touch-down spot because of its relative flatness, lack of boulders, and apparent abundance of fine-grained sand. Location Osprey is the backup. NASA plans to return soil samples for Bennu to Earth in 2023 for a detailed analysis. via NASA https://ift.tt/396Mpji

Solstice to Solstice Solargraph Timelapse

The 2019 December Solstice, on the first day of winter in planet Earth’s northern hemisphere and summer in the south, is at 4:19 Universal Time December 22. That’s December 21 for North America, though. Celebrate with a timelapse animation of the Sun’s seasonal progression through the sky. It was made with solargraph images from an ingenious array of 27 pinhole cameras. The first frame from the Solarcan camera matrix was recorded near December 21, 2018. The last frame in the series finished near June 21, 2019, the northern summer solstice. All 27 camera exposures were started at the same time, with a camera covered and removed from the array once a week. Viewed consecutively the pinhole camera pictures accumulate the traces of the Sun’s daily path from winter (bottom) to summer (top) solstice. Traces of the Sun’s path are reflected by the foreground Williestruther Loch, in the Scottish Borders. Just select the image or follow this link to play the entire 27 frame (gif) timelapse. via NASA https://ift.tt/35QjePy