Αστρονομική Εικόνα της Ημέρας από τη NASA

Προηγούμενες Αστρονομικές Εικόνες της Ημέρας από τη NASA

Moon Eclipses Saturn

27/08/2024

What if Saturn disappeared? Sometimes, it does. It doesn't really go away, though, it just disappears from view when our Moon moves in front. Such a Saturnian eclipse, more formally called an occultation, was visible along a long swath of Earth -- from Peru, across the Atlantic Ocean, to Italy -- only a few days ago. The featured color image is a digital fusion of the clearest images captured during the event and rebalanced for color and relative brightness between the relatively dim Saturn and the comparatively bright Moon. Saturn and the comparative bright Moon. The exposures were all taken from Breda, Catalonia, Spain, just before occultation. Eclipses of Saturn by our Moon will occur each month for the rest of this year. Each time, though, the fleeting event will be visible only to those with clear skies -- and the right location on Earth. Gallery: Moon Eclipses Saturn in August 2024

Perseid Meteors Over Inner Mongolia

26/08/2024

Did you see it? One of the more common questions during a meteor shower occurs because the time it takes for a meteor to flash is similar to the time it takes for a head to turn. Possibly, though, the glory of seeing bright meteors shoot across the sky -- while knowing that they were once small pebbles on another world -- might make it all worthwhile, even if your observing partner(s) can't always share in your experience. The featured video is composed of short clips taken in Inner Mongolia, China during the 2023 Perseid Meteor Shower. Several bright meteors were captured while live-reaction audio was being recorded -- just as the meteors flashed. This year's 2024 Perseids also produced many beautiful meteors. Another good meteor shower to watch for is the Geminids which peak yearly in mid-December, this year with relatively little competing glow from a nearly new Moon. Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Fresh Tiger Stripes on Saturn's Enceladus

25/08/2024

Do underground oceans vent through canyons on Saturn's moon Enceladus? Long features dubbed tiger stripes are known to be spewing ice from the moon's icy interior into space, creating a cloud of fine ice particles over the moon's South Pole and creating Saturn's mysterious E-ring. Evidence for this has come from the robot Cassini spacecraft that orbited Saturn from 2004 to 2017. Pictured here, a high resolution image of Enceladus is shown from a close flyby. The unusual surface features dubbed tiger stripes are visible in false-color blue. Why Enceladus is active remains a mystery, as the neighboring moon Mimas, approximately the same size, appears quite dead. An analysis of ejected ice grains has yielded evidence that complex organic molecules exist inside Enceladus. These large carbon-rich molecules bolster -- but do not prove -- that oceans under Enceladus' surface could contain life. Explore Your Universe: Random APOD Generator

South Pacific Shadowset

24/08/2024

The full Moon and Earth's shadow set together in this island skyscape. The alluring scene was captured Tuesday morning, August 20, from Fiji, South Pacific Ocean, planet Earth. For early morning risers shadowset in the western sky is a daily apparition. Still, the grey-blue shadow is often overlooked in favor of a brighter eastern horizon. Extending through the dense atmosphere, Earth's setting shadow is bounded above by a pinkish glow or anti-twilight arch. Known as the Belt of Venus, the arch's lovely color is due to backscattering of reddened light from the opposite horizon's rising Sun. Of course, the setting Moon's light is reddened by the long sight-line through the atmosphere. But on that date the full Moon could be called a seasonal Blue Moon, the third full Moon in a season with four full Moons. And even though the full Moon is always impressive near the horizon, August's full Moon is considered by some the first of four consecutive full Supermoons in 2024.

Supernova Remnant CTA 1

23/08/2024

There is a quiet pulsar at the heart of CTA 1. The supernova remnant was discovered as a source of emission at radio wavelengths by astronomers in 1960 and since identified as the result of the death explosion of a massive star. But no radio pulses were detected from the expected pulsar, the rotating neutron star remnant of the massive star's collapsed core. Seen about 10,000 years after the initial supernova explosion, the interstellar debris cloud is faint at optical wavelengths. CTA 1's visible wavelength emission from still expanding shock fronts is revealed in this deep telescopic image, a frame that spans about 2 degrees across a starfield in the northern constellation of Cepheus. While no pulsar has since been found at radio wavelengths, in 2008 the Fermi Gamma-ray Space Telescope detected pulsed emission from CTA 1, identifying the supernova remnant's rotating neutron star. The source has been recognized as the first in a growing class of pulsars that are quiet at radio wavelengths but pulse in high-energy gamma-rays.

The Dark Tower in Scorpius

22/08/2024

In silhouette against a crowded star field along the tail of the arachnological constellation Scorpius, this dusty cosmic cloud evokes for some the image of an ominous dark tower. In fact, monstrous clumps of dust and molecular gas collapsing to form stars may well lurk within the dark nebula, a structure that spans almost 40 light-years across this gorgeous telescopic portrait. A cometary globule, the swept-back cloud is shaped by intense ultraviolet radiation from the OB association of very hot stars in NGC 6231, off the upper right corner of the scene. That energetic ultraviolet light also powers the globule's bordering reddish glow of hydrogen gas. Hot stars embedded in the dust can be seen as bluish reflection nebulae. This dark tower and associated nebulae are about 5,000 light-years away. Growing Gallery: Moon Eclipses Saturn in August 2024

Fermi's 12-year All-Sky Gamma-ray Map

21/08/2024

Forget X-ray vision — imagine what you could see with gamma-ray vision! The featured all-sky map shows what the universe looks like to NASA's Fermi Gamma-ray Space Telescope. Fermi sees light with energies about a billion times what the human eye can see, and the map combines 12 years of Fermi observations. The colors represent the brightness of the gamma-ray sources, with brighter sources appearing lighter in color. The prominent stripe across the middle is the central plane of our Milky Way galaxy. Most of the red and yellow dots scattered above and below the Milky Way’s plane are very distant galaxies, while most of those within the plane are nearby pulsars. The blue background that fills the image is the diffuse glow of gamma-rays from distant sources that are too dim to be detected individually. Some gamma-ray sources remain unidentified and topics of research — currently no one knows what they are.

Supermoon Beyond the Temple of Poseidon

20/08/2024

A supermoon occurred yesterday. And tonight's moon should also look impressive. Supermoons appear slightly larger and brighter than most full moons because they reach their full phase when slightly nearer to the Earth -- closer than 90 percent of all full moons. This supermoon was also a blue moon given the definition that it is the third of four full moons occurring during a single season. Blue moons are not usually blue, and a different definition holds that a blue moon is the second full moon that occurs during a single month. The featured image captured the blue supermoon right near its peak size yesterday as it was rising beyond the Temple of Poseidon in Greece. This supermoon is particularly unusual in that it is the first of four successive supermoons, the next three occurring in September, October, and November.

Η Αστρονομική Εικόνα της Ημέρας από τη NASA

The Orion Nebula in Visible and Infrared

20/04/2025