NasaBot's Space

Sun Halo at Sixty-three Degrees North [apod.nasa.gov]

Happy Solstice!

Today is the December solstice, marking an astronomical beginning of summer in the southern hemisphere and winter in the north.

On its yearly trek through planet Earth's skies, at this solstice the Sun reaches its southern most declination, 23.5 degrees south, at 21:48 UTC.

About 4 days ago the Sun was near this seasonal southern limit and so only just above the horizon at local noon over Ostersund in central Sweden.

This view looking over the far northern lakeside city finds the midday Sun with a beautiful solar ice halo.

Naturally occurring atmospheric ice crystals can produce the tantalizing halo displays, refracting and reflecting the sunlight through their hexagonal geometry.

Still, with the Sun low and near the horizon in the clear sky, likely sources of the ice crystals producing this intense halo are snow cannons.

Operating at a local ski area, the snowmaking machines create a visible plume at the top of the nearby island Froson toward the right side of the panorama.

An Unusual Globule in IC 1396 [apod.nasa.gov]

Is there a monster in IC 1396?

Known to some as the Elephant's Trunk Nebula, parts of gas and dust clouds of this star formation region may appear to take on foreboding forms, some nearly human.

The only real monster here, however, is a bright young star too far from Earth to hurt us.

Energetic light from this star is eating away the dust of the dark cometary globule near the top of the featured image.

Jets and winds of particles emitted from this star are also pushing away ambient gas and dust.

Nearly 3,000 light-years distant, the relatively faint IC 1396 complex covers a much larger region on the sky than shown here, with an apparent width of more than 10 full moons.

Io in True Color [apod.nasa.gov]

The strangest moon in the Solar System is bright yellow.

The featured picture, an attempt to show how Io would appear in the "true colors" perceptible to the average human eye, was taken in 1999 July by the Galileo spacecraft that orbited Jupiter from 1995 to 2003.

Io's colors derive from sulfur and molten silicate rock.

The unusual surface of Io is kept very young by its system of active volcanoes.

The intense tidal gravity of Jupiter stretches Io and damps wobbles caused by Jupiter's other Galilean moons.

The resulting friction greatly heats Io's interior, causing

molten rock to explode through the surface.

Io's volcanoes are so active that they are effectively turning the whole moon inside out.

Some of Io's volcanic lava is so hot it glows in the dark.

Artemis 1 Coverage: Orion return and splashdown

America and the Sea of Serenity [apod.nasa.gov]

Get out your red/blue glasses and check out this stereo view of another world.

Fifty years ago the scene was recorded by Apollo 17 mission commander Eugene Cernan on December 11, 1972, one orbit before descending to land on the Moon.

The stereo anaglyph was assembled from two photographs (AS17-147-22465, AS17-147-22466) captured from his vantage point on board the Lunar Module Challenger as he and Dr. Harrison Schmitt flew over Apollo 17's landing site in the Taurus-Littrow Valley.

The broad, sunlit face of the mountain dubbed South Massif rises near the center of the frame, above the dark floor of Taurus-Littrow to its left.

Piloted by Ron Evans, the Command Module America is visible in orbit in the foreground against the South Massif's peak.

Beyond the mountains, toward the lunar limb, lies the Moon's Mare Serenitatis.

Mars Rises above the Lunar Limb [apod.nasa.gov]

On the night of December 7 Mars wandered near the Full Moon.

In fact the Red Planet was occulted, passing behind the Moon, when viewed from locations across Europe and North America.

About an hour after disappearing behind the lunar disk Mars reappears in this stack of sharp video frames captured from San Diego, planet Earth.

With the Moon in the foreground Mars was a mere 82 million kilometers distant, near its own opposition.

Full Moon and full Mars were bright enough provide the spectacular image with no exposure adjustments necessary.

In the image Mars appears to rise just over ancient, dark-floored, lunar crater Abel very close to the southeastern edge of the Moon's near side.

Humboldt is the large impact crater to its north (left).

Orion and the Ocean of Storms [apod.nasa.gov]

A camera on board the uncrewed Orion spacecraft captured this view on December 5 as Orion approached its return powered flyby of the Moon.

Below one of Orion's extended solar arrays lies dark, smooth, terrain along the western edge of the Oceanus Procellarum.

Prominent on the lunar nearside Oceanus Procellarum, the Ocean of Storms, is the largest of the Moon's lava-flooded maria.

The lunar terminator, shadow line between lunar night and day, runs along the left of the frame.

The 41 kilometer diameter crater Marius is top center, with ray crater Kepler peeking in at the edge, just right of the solar array wing.

Kepler's bright rays extend to the north and west, reaching the dark-floored Marius.

Of course the Orion spacecraft is now headed toward a December 11 splashdown in planet Earth's water-flooded Pacific Ocean.

NGC 7293: The Helix Nebula [apod.nasa.gov]

A mere seven hundred light years from Earth, toward the constellation Aquarius, a sun-like star is dying.

The dying star's last few thousand years have produced the Helix Nebula (NGC 7293), a well studied and nearby example of a Planetary Nebula, typical of this final phase of stellar evolution.

Combining narrow band image data from emission lines of hydrogen atoms in red and oxygen atoms in blue-green hues, it shows tantalizing details of the Helix, including its bright inner region about 3 light-years across.

The white dot at the Helix's center is this Planetary Nebula's hot, central star.

A simple looking nebula at first glance, the Helix is now understood to have a surprisingly complex geometry.

M16: A Star Forming Pillar from Webb [apod.nasa.gov]

What’s happening inside this interstellar mountain?

Stars are forming.

The mountain is actually a column of gas and dust in the picturesque Eagle Nebula (M16).

A pillar like this is so low in density that you could easily fly though it — it only appears solid because of its high dust content and great depth.

The glowing areas are lit internally by newly formed stars.

These areas shine in red and infrared light because blue light is scattered away by intervening interstellar dust.

The featured image was captured recently in near-infrared light in unprecedented detail by the James Webb Space Telescope (JWST), launched late last year.

Energetic light, abrasive winds, and final supernovas from these young stars will slowly destroy this stellar birth column over the next 100,000 years.

Astrophysicists: Browse 2,900+ codes in the Astrophysics Source Code Library

Pleiades: The Seven Sisters Star Cluster [apod.nasa.gov]

Have you ever seen the Pleiades star cluster?

Even if you have, you probably have never seen it as large and clear as this.

Perhaps the most famous star cluster on the sky, the bright stars of the Pleiades can be seen with the unaided eye even from the depths of a light-polluted city.

With a long exposure from a dark location, though, the dust cloud surrounding the Pleiades star cluster becomes very evident.

The featured 11-hour exposure, taken from the Siding Spring Observatory in Australia, covers a sky area several times the size of the full moon.

Also known as the Seven Sisters and M45, the Pleiades lies about 400 light years away toward the constellation of the Bull (Taurus).

A common legend with a modern twist is that one of the brighter stars faded since the cluster was named, leaving only six of the sister stars visible to the unaided eye.

The actual number of Pleiades stars visible, however, may be more or less than seven, depending on the darkness of the surrounding sky and the clarity of the observer's eyesight.

Your Sky Surprise: What picture did APOD feature on your birthday? (post 1995)

Video: Powers of Ten [apod.nasa.gov]

How different does the universe look on very small scales?

On very large scales?

The most famous short science film of its generation gives breathtaking comparisons.

That film, Powers of Ten, originally created in the 1960s, has been officially posted to YouTube and embedded here.

From a picnic blanket near Chicago out past the Virgo Cluster of Galaxies, every ten seconds the film zooms out to show a square a factor of ten times larger on each side.

The 9-minute video then reverses, zooming back in a factor of ten every two seconds and ends up inside a single proton.

The Powers of Ten sequence is actually based on the book Cosmic View by Kees Boeke in 1957, as is a similar but mostly animated film Cosmic Zoom that was also created in the late 1960s.

The changing perspectives are so enthralling and educational that sections have been recreated using more modern computerized techniques, including the first few minutes of the movie Contact.

Ray and husband Charles Eames, the film's creators, were known as quite visionary spirits and even invented their own popular chair.

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