How can gas float above the Sun? Twisted magnetic fields arching from the solar surface can trap ionized gas, suspending it in huge looping structures. These majestic plasma arches are seen as prominences above the solar limb. In 1999, this dramatic and detailed image was recorded by the Extreme ultraviolet Image Telescope (EIT) on board the space-based SOHO observatory in the light emitted by ionized Helium. It shows hot plasma escaping into space as a fiery prominence breaks free from magnetic confinement a hundred thousand kilometers above the Sun. These awesome events bear watching as they can affect communications and power systems over 100 million kilometers away on planet Earth. In late 2020 our Sun passed the solar minimum of its 11-year cycle and is now showing increased surface activity.
Named for the southern constellation toward which most of its galaxies can be found, the Fornax Cluster is one of the closest clusters of galaxies. About 62 million light-years away, it is almost 20 times more distant than our neighboring Andromeda Galaxy, and only about 10 percent farther than the better known and more populated Virgo Galaxy Cluster. Seen across this two degree wide field-of-view, almost every yellowish splotch on the image is an elliptical galaxy in the Fornax cluster. Elliptical galaxies NGC 1399 and NGC 1404 are the dominant, bright cluster members toward the upper left (but not the spiky foreground stars). A standout barred spiral galaxy NGC 1365 is visible on the lower right as a prominent Fornax cluster member.
The Mare Orientale, Latin for Eastern Sea, is one of the most striking large scale lunar features. The youngest of the large lunar impact basins it’s very difficult to see from an earthbound perspective. Still, taken during a period of favorable tilt, or libration of the lunar nearside, the Eastern Sea can be found near top center in this sharp telescopic view, extremely foreshortened along the Moon’s western edge. Formed by the impact of an asteroid over 3 billion years ago and nearly 1000 kilometers across, the impact basin’s concentric circular features, ripples in the lunar crust, are a little easier to spot in spacecraft images of the Moon, though. So why is the Eastern Sea at the Moon’s western edge? The Mare Orientale lunar feature was named before 1961. That’s when the convention labeling east and west on lunar maps was reversed.
South of the large star-forming region known as the Orion Nebula, lies bright blue reflection nebula NGC 1999. At the edge of the Orion molecular cloud complex some 1,500 light-years distant, NGC 1999’s illumination is provided by the embedded variable star V380 Orionis. The nebula is marked with a dark sideways T-shape at center right in this telescopic vista that spans about two full moons on the sky. Its dark shape was once assumed to be an obscuring dust cloud seen in silhouette. But infrared data suggest the shape is likely a hole blown through the nebula itself by energetic young stars. In fact, this region abounds with energetic young stars producing jets and outflows with luminous shock waves. Cataloged as Herbig-Haro (HH) objects, named for astronomers George Herbig and Guillermo Haro, the shocks have intense reddish hues. HH1 and HH2 are just below and right of NGC 1999. HH222, also known as the Waterfall nebula, looks like a red gash near top right in the frame. To create the shocks stellar jets push through the surrounding material at speeds of hundreds of kilometers per second.
Why is the sky near Antares and Rho Ophiuchi so dusty yet colorful? The colors result from a mixture of objects and processes. Fine dust — illuminated from the front by starlight — produces blue reflection nebulae. Gaseous clouds whose atoms are excited by ultraviolet starlight produce reddish emission nebulae. Backlit dust clouds block starlight and so appear dark. Antares, a red supergiant and one of the brighter stars in the night sky, lights up the yellow-red clouds on the lower right of the featured image. The Rho Ophiuchi star system lies at the center of the blue reflection nebula on the top left. The distant globular cluster of stars M4 is visible above and to the right of Antares. These star clouds are even more colorful than humans can see, emitting light across the electromagnetic spectrum.
Which direction is this comet heading? Judging by the tail, one might imagine that Comet Leonard is traveling towards the bottom right, but a full 3D analysis shows it traveling almost directly away from the camera. With this perspective, the dust tail is trailed towards the camera and can only be seen as a short yellow-white glow near the head of the comet. The bluish ion tail, however, is made up of escaping ions that are forced directly away from the Sun by the solar wind — but channeled along the Sun’s magnetic field lines. The Sun’s magnetic field is quite complex, however, and occasionally solar magnetic reconnection will break the ion tail into knots that are pushed away from the Sun. One such knot is visible in the featured one-hour time-lapse video captured in late December from Thailand. Comet Leonard is now fading as it heads out of our Solar System.
By starlight this eerie visage shines in the dark, a crooked profile evoking its popular name, the Witch Head Nebula. In fact, this entrancing telescopic portrait gives the impression that the witch has fixed her gaze on Orion’s bright supergiant star Rigel. More formally known as IC 2118, the Witch Head Nebula spans about 50 light-years and is composed of interstellar dust grains reflecting Rigel’s starlight. The blue color of the Witch Head Nebula and of the dust surrounding Rigel is caused not only by Rigel‘s intense blue starlight but because the dust grains scatter blue light more efficiently than red. The same physical process causes Earth’s daytime sky to appear blue, although the scatterers in Earth’s atmosphere are molecules of nitrogen and oxygen. Rigel, the Witch Head Nebula, and gas and dust that surrounds them lie about 800 light-years away.
Seen from ice moon Tethys, rings and shadows would display fantastic views of the Saturnian system. Haven’t dropped in on Tethys lately? Then this gorgeous ringscape from the Cassini spacecraft will have to do for now. Caught in sunlight just below and left of picture center in 2005, Tethys itself is about 1,000 kilometers in diameter and orbits not quite five saturn-radii from the center of the gas giant planet. At that distance (around 300,000 kilometers) it is well outside Saturn’s main bright rings, but Tethys is still one of five major moons that find themselves within the boundaries of the faint and tenuous outer E ring. Discovered in the 1980s, two very small moons Telesto and Calypso are locked in stable along Tethys’ orbit. Telesto precedes and Calypso follows Tethys as the trio circles Saturn.
On Monday, January’s Full Moon rose as the Sun set. Spotted near the eastern horizon, its warm hues are seen in this photo taken near Cagliari, capital city of the Italian island of Sardinia. Of course the familiar patterns of light and dark across the Moon’s nearside are created by bright rugged highlands and dark smooth lunar maria. Traditionally the patterns are seen as pareidolia, giving the visual illusion of a human face like the Man in the Moon, or familiar animal like the Moon rabbit. But for a moment the swarming murmuration, also known as a flock of starlings, frozen in the snapshot’s field of view lends another pareidolic element to the scene. Some see the graceful figure of a dancer enchanted by moonlight.
Laser guide stars and adaptive optics sharpened this stunning ground-based image of stellar jets from the Gemini South Observatory, Chilean Andes, planet Earth. These twin outflows of MHO 2147 are from a young star in formation. It lies toward the central Milky Way and the boundary of the constellations Sagittarius and Ophiuchus at an estimated distance of some 10,000 light-years. At center, the star itself is obscured by a dense region of cold dust. But the infrared image still traces the sinuous jets across a frame that would span about 5 light-years at the system’s estimated distance. Driven outward by the young rotating star, the apparent wandering direction of the jets is likely due to precession. Part of a multiple star system, the young star’s rotational axis would slowly precess or wobble like a top under the gravitation influence of its nearby companions.