Sander Meijer
boosted
Comet Lemmon over the High Tatras
Image Credit & Copyright: Tomáš Slovinský & Constantine Themelis
Explanation: Comet Lemmon putting on a show for cameras around the globe. Passing nearest to the Earth this week, the photogenic comet C/2025 A6 (Lemmon) is now extending two long tails : a blue ion tail and a white dust tail. The ion tail is pushed away from the Sun by the ever-present by ever-changing solar wind, and shows structure also created by how much gas is ejected at any one moment. It glows because it is ionized by high energy sunlight. The dust tail is pushed away from the comet by sunlight and shines by reflecting sunlight. The featured image is an enhanced composite of 50 exposures all taken two days ago from Mlynica, Slovakia. The mountains in the foreground are the High Tatras that partly separate Slovakia from Poland. Although Comet Lemmon is best visible in long camera exposures, the shedding ice ball has become faintly visible in northern skies even to unaided eyes through dark skies toward the west after sunset.
Comet Lemmon over the High Tatras
Image Credit & Copyright: Tomáš Slovinský & Constantine Themelis
Explanation: Comet Lemmon putting on a show for cameras around the globe. Passing nearest to the Earth this week, the photogenic comet C/2025 A6 (Lemmon) is now extending two long tails : a blue ion tail and a white dust tail. The ion tail is pushed away from the Sun by the ever-present by ever-changing solar wind, and shows structure also created by how much gas is ejected at any one moment. It glows because it is ionized by high energy sunlight. The dust tail is pushed away from the comet by sunlight and shines by reflecting sunlight. The featured image is an enhanced composite of 50 exposures all taken two days ago from Mlynica, Slovakia. The mountains in the foreground are the High Tatras that partly separate Slovakia from Poland. Although Comet Lemmon is best visible in long camera exposures, the shedding ice ball has become faintly visible in northern skies even to unaided eyes through dark skies toward the west after sunset.
Marc
and 1 other
boosted
Finding Comet Lemmon
Image Credit & Copyright: Petr Horalek / Institute of Physics in Opava
Explanation: Tonight, if you can see the stars of the Big Dipper, then you can find comet Lemmon in your evening sky. After sunset, look for the faint but extended comet above your northwestern horizon -- but below the handle of the famous celestial kitchen utensil of the north. It might be easier to see this visitor to the inner Solar System through your camera phone, which is better at picking up faint objects. Either way, look for a fuzzy green 'star' with a tail, though probably not so long a tail as in this impressive snapshot taken over Seč Lake in the Czech Republic two nights ago. Recent photographs of C/2025 A6 (Lemmon) often show a detailed and changing ion tail which extends farther than the eye can follow. This Sun-orbiting comet is now near its closest approach to Earth and will pass its closest to the Sun in early November.
Finding Comet Lemmon
Image Credit & Copyright: Petr Horalek / Institute of Physics in Opava
Explanation: Tonight, if you can see the stars of the Big Dipper, then you can find comet Lemmon in your evening sky. After sunset, look for the faint but extended comet above your northwestern horizon -- but below the handle of the famous celestial kitchen utensil of the north. It might be easier to see this visitor to the inner Solar System through your camera phone, which is better at picking up faint objects. Either way, look for a fuzzy green 'star' with a tail, though probably not so long a tail as in this impressive snapshot taken over Seč Lake in the Czech Republic two nights ago. Recent photographs of C/2025 A6 (Lemmon) often show a detailed and changing ion tail which extends farther than the eye can follow. This Sun-orbiting comet is now near its closest approach to Earth and will pass its closest to the Sun in early November.
Alex, the Hearth Fire
boosted
All the Water on Europa
Illustration Credit & Copyright: Kevin Hand (JPL/Caltech), Jack Cook (Woods Hole Oceanographic Institution), & Howard Perlman (USGS)
Explanation: How much of Jupiter's moon Europa is made of water? No one is sure, but probably a lot. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa possesses a deep, global ocean of liquid water beneath a layer of surface ice. The subsurface ocean plus ice layer could descend over 100 kilometers in average depth. Adopting a high-end estimate of 100 kilometers depth, if all the water on Europa were gathered into a ball, it would have a radius of over 800 kilometers. To scale, this intriguing illustration compares that hypothetical ball of all the water on Europa to the size of Europa itself (left) - and similarly to all the water on planet Earth. With a volume possibly greater than Earth's oceans, the global subsurface ocean on Europa is a tantalizing destination to search for extraterrestrial life in our Solar System. NASA's robotic Europa Clipper was launched last year to investigate.
All the Water on Europa
Illustration Credit & Copyright: Kevin Hand (JPL/Caltech), Jack Cook (Woods Hole Oceanographic Institution), & Howard Perlman (USGS)
Explanation: How much of Jupiter's moon Europa is made of water? No one is sure, but probably a lot. Based on the Galileo probe data acquired during its exploration of the Jovian system from 1995 to 2003, Europa possesses a deep, global ocean of liquid water beneath a layer of surface ice. The subsurface ocean plus ice layer could descend over 100 kilometers in average depth. Adopting a high-end estimate of 100 kilometers depth, if all the water on Europa were gathered into a ball, it would have a radius of over 800 kilometers. To scale, this intriguing illustration compares that hypothetical ball of all the water on Europa to the size of Europa itself (left) - and similarly to all the water on planet Earth. With a volume possibly greater than Earth's oceans, the global subsurface ocean on Europa is a tantalizing destination to search for extraterrestrial life in our Solar System. NASA's robotic Europa Clipper was launched last year to investigate.
Doug Belshaw
boosted
The Rotating Moon
Video Credit: NASA, Lunar Reconnaissance Orbiter, Arizona State U.
Explanation: No one on Earth sees the Moon rotate like this. That's because the Moon is tidally locked in synchronous rotation, showing only one side to denizens of our fair planet. Still, given modern digital technology, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie can be composed. In fact, the featured time-lapse video starts with a view of the familiar lunar nearside and quickly finds the Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotating into view just below the equator. In a complete lunar rotation condensed into 24 seconds, the video clearly shows that the Earth-facing nearside of the Moon contains an abundance of dark lunar maria, while the lunar farside is dominated by bright lunar highlands. Of course, you can just join other moon-watchers under hopefully clear skies tonight. Check out the sunlit portion of the lunar nearside on International Observe the Moon Night.
The Rotating Moon
Video Credit: NASA, Lunar Reconnaissance Orbiter, Arizona State U.
Explanation: No one on Earth sees the Moon rotate like this. That's because the Moon is tidally locked in synchronous rotation, showing only one side to denizens of our fair planet. Still, given modern digital technology, combined with many detailed images returned by the Lunar Reconnaissance Orbiter (LRO), a high resolution virtual Moon rotation movie can be composed. In fact, the featured time-lapse video starts with a view of the familiar lunar nearside and quickly finds the Mare Orientale, a large crater with a dark center that is difficult to see from the Earth, rotating into view just below the equator. In a complete lunar rotation condensed into 24 seconds, the video clearly shows that the Earth-facing nearside of the Moon contains an abundance of dark lunar maria, while the lunar farside is dominated by bright lunar highlands. Of course, you can just join other moon-watchers under hopefully clear skies tonight. Check out the sunlit portion of the lunar nearside on International Observe the Moon Night.
Alex Akselrod
and 1 other
boosted
Two Camera Comets in One Sky https://apod.nasa.gov/apod/ap250929.html #APOD
Alex, the Hearth Fire
boosted
Two Camera Comets in One Sky
Image Credit & Copyright: Luc Perrot (TWAN)
Explanation: https://apod.nasa.gov/apod/ap250929.html #APOD
Two Camera Comets in One Sky
Image Credit & Copyright: Luc Perrot (TWAN)
Explanation: https://apod.nasa.gov/apod/ap250929.html #APOD
Two Camera Comets in One Sky https://apod.nasa.gov/apod/ap250929.html #APOD
Alex, the Hearth Fire
boosted
A SWAN, an ATLAS, and Mars
Image Credit & Copyright: Adam Block
Explanation: https://apod.nasa.gov/apod/ap250926.html #APOD
A SWAN, an ATLAS, and Mars
Image Credit & Copyright: Adam Block
Explanation: https://apod.nasa.gov/apod/ap250926.html #APOD
jaz :twt: :wales_flag:
boosted
#NGC6357: Cathedral to Massive #Stars
#Astronomy #Picture of the Day
Alex, the Hearth Fire
boosted
GW250114: Rotating Black Holes Collide
Illustration Credit: Aurore Simonnet (SSU/EdEon), LVK, URI; LIGO Collaboration
Explanation: https://apod.nasa.gov/apod/ap250924.html #APOD
