2023 September 29
Explanation: Back from asteroid 101955 Bennu, a 110-pound, 31-inch wide sample return capsule rests in a desert on planet Earth in this photo, taken at the Department of Defense Utah Test and Training Range near Salt Lake City last Sunday, September 24. Dropped off by the OSIRIS-Rex spacecraft, the capsule looks charred from the extreme temperatures experienced during its blistering descent through Earth's dense atmosphere. OSIRIS-Rex began its home-ward journey from Bennu in May of 2021. Delivered to NASA’s Johnson Space Center in Houston on September 25, the capsule's canister is expected to contain an uncontaminated sample of about a half pound (250 grams) of Bennu's loosely packed regolith. Working in a new laboratory designed for the OSIRIS-REx mission, scientists and engineers will complete the canister disassembly process, and plan to unveil the sample of the near-Earth asteroid in a broadcast event on October 11.
2023 September 28
Explanation: Ridges of glowing interstellar gas and dark dust clouds inhabit the turbulent, cosmic depths of the Lagoon Nebula. Also known as M8, The bright star forming region is about 5,000 light-years distant. It makes for a popular stop on telescopic tours of the constellation Sagittarius toward the center of our Milky Way Galaxy. Dominated by the telltale red emission of ionized hydrogen atoms recombining with stripped electrons, this deep telescopic view of the Lagoon's central reaches is about 40 light-years across. The bright hourglass shape near the center of the frame is gas ionized and sculpted by energetic radiation and extreme stellar winds from a massive young star.
2023 September 27
Explanation: Not every road ends in a STEVE. A week ago, a sky enthusiast's journey began with a goal: to photograph an aurora over Lake Huron. Driving through rural Ontario, Canada, the forecasted sky show started unexpectedly early, causing the photographer to stop before arriving at the scenic Great Lake. Aurora images were taken toward the north -- but over land, not sea. While waiting for a second round of auroras, a peculiar band of light was noticed to the west. Slowly, the photographer and friends realized that this western band was likely an unusual type of aurora: a Strong Thermal Emission Velocity Enhancement (STEVE). Moreover, this STEVE was putting on quite a show: appearing intertwined with the central band of our Milky Way Galaxy while intersecting the horizon just near the end of the country road. After capturing this cosmic X on camera, the photographer paused to appreciate the unexpected awesomeness of finding extraordinary beauty in an ordinary setting.
2023 September 24
Explanation: What's rising above the horizon behind those clouds? It's the Sun. Most sunrises don't look like this, though, because most sunrises don't include the Moon. In the early morning of 2013 May 10, however, from Western Australia, the Moon was between the Earth and the rising Sun. At times, it would be hard for the uninformed to understand what was happening. In an annular eclipse, the Moon is too far from the Earth to block the entire Sun, and at most leaves a ring of fire where sunlight pours out around every edge of the Moon. The featured time-lapse video also recorded the eclipse through the high refraction of the Earth's atmosphere just above the horizon, making the unusual rising Sun and Moon appear also flattened. As the video continues, the Sun continues to rise, while the Sun and Moon begin to separate. The next annular solar eclipse will occur in less than three weeks. On Saturday, October 14, a ring of fire will be visible through clear skies from a thin swath crossing both North and South America.
2023 September 23
Explanation: An analemma is that figure-8 curve you get when you mark the position of the Sun at the same time each day for one year. To make this one, a 4x5 pinhole camera was set up looking north in southern New Zealand skies. The shutter was briefly opened each clear day in the afternoon at 4pm local time exposing the same photosensitized glass plate for the year spanning September 23, 2022 to September 19, 2023. On two days, the winter and summer solstices, the shutter was opened again 15 minutes after the main exposure and remained open until sunset to create the sun trails at the bottom and top of the curve. The equinox dates correspond to positions in the middle of the curve, not the crossover point. Of course, the curve itself is inverted compared to an analemma traced from the northern hemisphere. And while fall begins today at the Autumnal Equinox for the northern hemisphere, it's the Spring Equinox in the south.
2023 September 21
Explanation: During the day, over 12,000 large mirrors reflect sunlight at the 100-megawatt, molten-salt, solar thermal power plant at the western edge of the Gobi desert near Dunhuang, Gansu Province, China. Individual mirror panels turn to track the sun like sunflowers. They conspire to act as a single super mirror reflecting the sunlight toward a fixed position, the power station's central tower. During the night the mirrors stand motionless though. They reflect the light of the countless distant stars, clusters and nebulae of the Milky Way and beyond. This sci-fi night skyscape was created with a camera fixed to a tripod near the edge of the giant mirror matrix on September 15. The camera's combined sequence of digital exposures captures concentric arcs of celestial star trails through the night with star trails in surreal mirrored reflection.
La distance de cette galaxie a été mesurée précisément grâce aux Céphéides qu'on y observe. Elle est située à 108 millions d' anné...
.svg){kind=link}