NasaBot's Space

Unraveling NGC 3169 [apod.nasa.gov]

Spiral galaxy NGC 3169 looks to be unraveling like a ball of cosmic yarn.

It lies some 70 million light-years away, south of bright star Regulus toward the faint constellation Sextans.

Wound up spiral arms are pulled out into sweeping tidal tails as NGC 3169 (left) and neighboring NGC 3166 interact gravitationally.

Eventually the galaxies will merge into one, a common fate even for bright galaxies in the local universe.

Drawn out stellar arcs and plumes are clear indications of the ongoing gravitational interactions across the deep and colorful galaxy group photo.

The telescopic frame spans about 20 arc minutes or about 400,000 light-years at the group's estimated distance, and includes smaller, bluish NGC 3165 at the right.

NGC 3169 is also known to shine across the spectrum from radio to X-rays, harboring an active galactic nucleus that is the site of a supermassive black hole.

The Flaming Star Nebula [apod.nasa.gov]

Is star AE Aurigae on fire? No.

Even though AE Aurigae is named the Flaming Star and the surrounding nebula IC 405 is named the Flaming Star Nebula, and even though the nebula appears to some like a swirling flame, there is no fire.

Fire, typically defined as the rapid molecular acquisition of oxygen, happens only when sufficient oxygen is present and is not important in such high-energy, low-oxygen environments such as stars.

The bright star AE Aurigae occurs near the center of the Flaming Star Nebula and is so hot it glows blue, emitting light so energetic it knocks electrons away from surrounding gas.

When a proton recaptures an electron, light is emitted, as seen in the surrounding emission nebula.

Captured here three weeks ago, the Flaming Star Nebula is visible near the composite image's center, between the red Tadpole Nebula on the left and blue-tailed Comet ZTF on the right.

The Flaming Star Nebula lies about 1,500 light years distant, spans about 5 light years, and is visible with a small telescope toward the constellation of the Charioteer (Auriga).

Crescent Moon Beyond Greek Temple [apod.nasa.gov]

Why is a thin crescent moon never seen far from a horizon?

Because the only geometry that gives a thin crescent lunar phase occurs when the Moon appears close to the Sun in the sky.

The crescent is not caused by the shadow of the Earth, but by seeing only a small part of the Moon directly illuminated by the Sun.

Moreover, the thickest part of the crescent always occurs in the direction of the Sun.

In the evening, a thin crescent Moon will set shortly after the Sun and not be seen for the rest of the night.

Alternatively, in the morning, a crescent Moon will rise shortly before the Sun after not being seen for most of the night.

Pictured two weeks ago, a crescent moon was captured near the horizon, just before sunrise, far behind remnants of the ancient Temple of Poseidon in Greece.

Zodiacal Ray with Venus and Jupiter [apod.nasa.gov]

What's causing that unusual ray of light extending from the horizon?

Dust orbiting the Sun.

At certain times of the year, a band of sun-reflecting dust from the inner Solar System appears prominently after sunset or before sunrise and is called zodiacal light.

The dust was emitted mostly from faint Jupiter-family comets and slowly spirals into the Sun.

The featured HDR image, acquired in mid-February from the Sierra Nevada National Park in Spain, captures the glowing band of zodiacal light going right in front of the bright evening planets Jupiter (upper) and Venus (lower).

Emitted from well behind the zodiacal light is a dark night sky that prominently includes the Pleiades star cluster.

Jupiter and Venus are slowly switching places in the evening sky, and just in the next few days nearing their closest angular approach.

Saturn's Iapetus: Moon with a Strange Surface [apod.nasa.gov]

What would make a moon look like a walnut?

A strange ridge that circles Saturn's moon Iapetus's equator, visible near the bottom of the featured image, makes it appear similar to a popular edible nut.

The origin of the ridge remains unknown, though, with hypotheses including ice that welled up from below, a ring that crashed down from above, and structure left over from its formation perhaps 100 million years ago.

Also strange is that about half of Iapetus is so dark that it can nearly disappear when viewed from Earth, while the rest is, reflectively, quite bright.

Observations show that the degree of darkness of the terrain is strangely uniform, as if a dark coating was somehow recently applied to an ancient and highly cratered surface.

Last, several large impact basins occur around Iapetus, with a 400-kilometer wide crater visible near the image center, surrounded by deep cliffs that drop sharply to the crater floor.

The featured image was taken by the Saturn-orbiting Cassini spacecraft during a flyby of Iapetus at the end of 2004.

Crescent Moon Occultation [apod.nasa.gov]

On February 22, a young Moon shared the western sky at sunset with bright planets Venus and Jupiter along the ecliptic plane.

The beautiful celestial conjunction was visible around planet Earth.

But from some locations Jupiter hid for a while, occulted by the crescent lunar disk.

The Solar System's ruling gas giant was captured here just before it disappeared behind the the Moon's dark edge, seen over the Río de la Plata at Colonia del Sacramento, Uruguay.

In the serene river and skyscape Venus is not so shy, shining brightly closer to the horizon through the fading twilight.

Next week Venus and Jupiter will appear even closer in your evening sky.

Jones-Emberson 1 [apod.nasa.gov]

Planetary nebula Jones-Emberson 1 is the death shroud of a dying Sun-like star.

It lies some 1,600 light-years from Earth toward the sharp-eyed constellation Lynx.

About 4 light-years across, the expanding remnant of the dying star's atmosphere was shrugged off into interstellar space, as the star's central supply of hydrogen and then helium for fusion was finally depleted after billions of years.

Visible near the center of the planetary nebula is what remains of the stellar core, a blue-hot white dwarf star.

Also known as PK 164 +31.1, the nebula is faint and very difficult to glimpse at a telescope's eyepiece.

But this deep broadband image combining 22 hours of exposure time does show it off in exceptional detail.

Stars within our own Milky Way galaxy as well as background galaxies across the universe are scattered through the clear field of view.

Ephemeral on the cosmic stage, Jones-Emberson 1 will fade away over the next few thousand years.

Its hot, central white dwarf star will take billions of years to cool.

Arp 78: Peculiar Galaxy in Aries [apod.nasa.gov]

Peculiar spiral galaxy Arp 78 is found within the boundaries of the head strong constellation Aries.

Some 100 million light-years beyond the stars and nebulae of our Milky Way galaxy, the island universe is an enormous 200,000 light-years across.

Also known as NGC 772, it sports a prominent, outer spiral arm in this detailed cosmic portrait.

Tracking along sweeping dust lanes and lined with young blue star clusters, Arp 78's overdeveloped spiral arm is pumped-up by galactic-scale gravitational tides.

Interactions with its brightest companion galaxy, the more compact NGC 770 seen above and right of the larger spiral, are likely responsible.

Embedded in faint star streams revealed in the deep telescopic exposure, NGC 770's fuzzy, elliptical appearance contrasts nicely with spiky foreground Milky Way stars in matching yellowish hues.

Our Increasingly Active Sun [apod.nasa.gov]

Our Sun is becoming a busy place.

Only two years ago, the Sun was emerging from a solar minimum so quiet that months would go by without even a single sunspot.

In contrast, already this year and well ahead of schedule, our Sun is unusually active, already nearing solar activity levels seen a decade ago during the last solar maximum.

Our increasingly active Sun was captured two weeks ago sporting numerous interesting features.

The image was recorded in a single color of light called Hydrogen Alpha, color-inverted, and false colored.

Spicules carpet much of the Sun's face.

The brightening towards the Sun's edges is caused by increased absorption of relatively cool solar gas and called limb darkening.

Just outside the Sun's disk, several scintillating prominences protrude, while prominences on the Sun's face are known as filaments and show as light streaks.

Magnetically tangled active regions are both dark and light and contain cool sunspots.

As our Sun's magnetic field winds toward solar maximum over the next few years, whether the Sun's high activity will continue to increase is unknown.

Comet ZTF over Yosemite Falls [apod.nasa.gov]

They are both falling.

The water in Yosemite Falls, California, USA, is falling toward the Earth.

Comet ZTF is falling toward the Sun.

This double cosmic cascade was captured late last month as fading Comet C/2022 E3 (ZTF) had just passed its closest to planet Earth.

The orange star just over the falls is Kochab.

With the exception of a brief encounter with a black bear, the featured image was a well-planned composite of a moonlit-foreground and long-duration background exposures - all designed to reconstruct a deep version of an actual single sight.

Although Comet ZTF is now fading as it glides back to the outer Solar System, its path is determined by gravity and so it can be considered to still be falling toward the Sun — but backwards.

Comet ZTF Gallery: Notable Submissions to APOD