Η Αστρονομική Εικόνα της Ημέρας από τη NASA
Interplanetary Earth
23/11/2024
In an interplanetary first, on July 19, 2013 Earth was photographed on the same day from two other worlds of the Solar System, innermost planet Mercury and ringed gas giant Saturn. Pictured on the left, Earth is the pale blue dot just below the rings of Saturn, as captured by the robotic Cassini spacecraft then orbiting the outermost gas giant. On that same day people across planet Earth snapped many of their own pictures of Saturn. On the right, the Earth-Moon system is seen against the dark background of space as captured by the sunward MESSENGER spacecraft, then in Mercury orbit. MESSENGER took its image as part of a search for small natural satellites of Mercury, moons that would be expected to be quite dim. In the MESSENGER image, the brighter Earth and Moon are both overexposed and shine brightly with reflected sunlight. Destined not to return to their home world, both Cassini and MESSENGER have since retired from their missions of Solar System exploration.
Copyright: NASA
Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA
NGC 7023: The Iris Nebula
02/09/2023
These cosmic clouds have blossomed 1,300 light-years away in the fertile starfields of the constellation Cepheus. Called the Iris Nebula, NGC 7023 is not the only nebula to evoke the imagery of flowers. Still, this deep telescopic image shows off the Iris Nebula's range of colors and symmetries embedded in surrounding fields of interstellar dust. Within the Iris itself, dusty nebular material surrounds a hot, young star. The dominant color of the brighter reflection nebula is blue, characteristic of dust grains reflecting starlight. Central filaments of the reflection nebula glow with a faint reddish photoluminescence as some dust grains effectively convert the star's invisible ultraviolet radiation to visible red light. Infrared observations indicate that this nebula contains complex carbon molecules known as PAHs. The dusty blue petals of the Iris Nebula span about six light-years.
Copyright: Lorand Fenyes
The Great Globular Cluster in Hercules
01/09/2023
In 1716, English astronomer Edmond Halley noted, "This is but a little Patch, but it shows itself to the naked Eye, when the Sky is serene and the Moon absent." Of course, M13 is now less modestly recognized as the Great Globular Cluster in Hercules, one of the brightest globular star clusters in the northern sky. Sharp telescopic views like this one reveal the spectacular cluster's hundreds of thousands of stars. At a distance of 25,000 light-years, the cluster stars crowd into a region 150 light-years in diameter. Approaching the cluster core, upwards of 100 stars could be contained in a cube just 3 light-years on a side. For comparison, the closest star to the Sun is over 4 light-years away. The remarkable range of brightness recorded in this image follows stars into the dense cluster core.
Copyright: Serge Brunier, Jean-François Bax, David Vernet
The Crew-7 Nebula
31/08/2023
Not the James Webb Space Telescope's latest view of a distant galactic nebula, this illuminated cloud of gas and dust dazzled early morning spacecoast skygazers on August 26. The snapshot was taken about 2 minutes after the launch of a Falcon 9 rocket on the SpaceX Crew-7 mission, the seventh commercial crew rotation mission for the International Space Station. It captures drifting plumes and exhaust from the separated first and second stage illuminated against the still dark skies. Near the center of the image, within the ragged blueish ring, are two bright points of light. The lower one is the second stage of the rocket carrying 4 humans to space in a Crew Dragon spacecraft. The bright point above is the Falcon 9 first stage booster orienting itself for the trip back to Landing Zone-1 at Cape Canaveral, planet Earth.
Copyright: Michael Seeley
Full Moons of August
30/08/2023
Near perigee, the closest point in its almost moonthly orbit, a Full Moon rose as the Sun set on August 1. Its brighter than average lunar disk was captured in this dramatic moonrise sequence over dense cloud banks along the eastern horizon from Ragusa, Sicily. Illuminating night skies around planet Earth it was the second supermoon of 2023. Yet again near perigee, the third supermoon of 2023 will also shine on an August night. Rising as the Sun sets tonight this second Full Moon in August will be known to some as a Blue Moon, even though scattered sunlight gives the lunar disk a reddened hue. Defined as the second full moon in a calendar month, blue moons occur only once every 2 or 3 years. That's because lunar phases take 29.5 days, almost a calendar month, to go through a complete cycle. Tonight an August Blue Moon will find itself beside bright planet Saturn.
Copyright: Gianni Tumino
Unusual Spiral Galaxy M66 from Webb
29/08/2023
Why isn't spiral galaxy M66 symmetric? Usually, density waves of gas, dust, and newly formed stars circle a spiral galaxy's center and create a nearly symmetric galaxy. The differences between M66's spiral arms and the apparent displacement of its nucleus are all likely caused by previous close interactions and the tidal gravitational pulls of nearby galaxy neighbors M65 and NGC 3628. The galaxy, featured here in infrared light taken by the James Webb Space Telescope, spans about 100,000 light years, lies about 35 million light years distant, and is the largest galaxy in a group known as the Leo Triplet. Like many spiral galaxies, the long and intricate dust lanes of M66 are seen intertwined with the bright stars and intergalactic dust that follow the spiral arms.
Copyright: NASA
Star Formation in the Pacman Nebula
28/08/2023
Look through the cosmic cloud cataloged as NGC 281 and you might miss the stars of open cluster IC 1590. Formed within the nebula, that cluster's young, massive stars ultimately power the pervasive nebular glow. The eye-catching shapes looming in the featured portrait of NGC 281 are sculpted dusty columns and dense Bok globules seen in silhouette, eroded by intense, energetic winds and radiation from the hot cluster stars. If they survive long enough, the dusty structures could also be sites of future star formation. Playfully called the Pacman Nebula because of its overall shape, NGC 281 is about 10,000 light-years away in the constellation Cassiopeia. This sharp composite image was made through narrow-band filters. It combines emission from the nebula's hydrogen and oxygen atoms to synthesize red, green, and blue colors. The scene spans well over 80 light-years at the estimated distance of NGC 281.
Copyright: Craig Stocks
Three Galaxies and a Comet
27/08/2023
Diffuse starlight and dark nebulae along the southern Milky Way arc over the horizon and sprawl diagonally through this gorgeous nightscape. The breath-taking mosaic spans a wide 100 degrees, with the rugged terrain of the Patagonia, Argentina region in the foreground. Along with the insider's view of our own galaxy, the image features our outside perspective on two irregular satellite galaxies - the Large and Small Magellanic Clouds. The scene also captures the broad tail and bright coma of Comet McNaught, the Great Comet of 2007.
Copyright: Miloslav Druckmuller (Brno University of Technology)
Crescents of Venus
26/08/2023
Just as the Moon goes through phases, Venus' visible sunlit hemisphere waxes and wanes. This sequence of telescopic images illustrates the steady changes for Venus during its recent 2023 apparition as our evening star. Gliding along its interior orbit between Earth and Sun, Venus grows larger during that period because it is approaching planet Earth. Its crescent narrows though, as the inner planet swings closer to our line-of-sight to the Sun. Closest to the Earth-Sun line but passing about 8 degrees south of the Sun, on August 13 Venus reached its (non-judgmental) inferior conjunction. And now Venus shines above the eastern horizon in predawn skies, completing its transition to planet Earth's morning star. On August 21, NASA's Parker Solar Probe completed its sixth gravity assist flyby of Venus, using the encounter to maneuver the probe toward its closest approach yet to the Sun.
Copyright: Roberto Ortu
Η Αστρονομική Εικόνα της Ημέρας από τη NASA (NASA Astronomy Picture of the Day) είναι μια δωρεάν υπηρεσία που παρέχει καθημερινά μια εντυπωσιακή εικόνα από το σύμπαν, την λήψη της οποίας έχει πραγματοποιήσει κάποιος από τους αστρονόμους της NASA ή από κάποιον από τους δορυφόρους ή τα τηλεσκόπια που η NASA λειτουργεί. Οι εικόνες που εμφανίζονται καλύπτουν μια ευρεία γκάμα από θέματα, συμπεριλαμβανομένων των αστερισμών, των γαλαξιών, των πλανητικών συστημάτων, των κομητών, των αστρικών σωμάτων και των παρατηρητηρίων. Κάθε εικόνα συνοδεύεται από μια σύντομη εξήγηση και πληροφορίες σχετικά με το τι παρατηρείται στην εικόνα.