A Colossal Shell of Light. Spirals of dust swirl across trillions of kilometers of interstellar space as an expanding halo of light around a distant star, named V838 Monocerotis illuminates the giant cloud. The glow comes from the red supergiant star at the middle of the image, which gave off a flashbulb-like pulse of light, This image shows the progress the light-pulse had made after two years of traveling away from the star in all directions, imaged by Hubble on February 8, 2004. V838 Monocerotis is located about 20,000 light-years away from Earth in the direction of the constellation Monoceros, at the outer edge of our Milky Way galaxy. #

A Spectacular Spiral. This celestial object, spiral galaxy M100, is seen here as observed by Hubble's Wide Field Camera 3, which was installed on a servicing mission in 2009 to provide enhanced imaging capability. M100 is designated a grand-design spiral galaxy because of its two prominent lanes of young, blue stars. This is caused by ripples of matter in the stellar disk that propagate through the galaxy and create high-density regions of gas. These denser areas precipitate new star formation.The yellowish color of the inner region is from older populations of stars. #

Summertime on Saturn. Hubble observed Saturn and its rings on June 20, 2019, as the planet was near its closest approach to Earth, about 845 million miles away (1.36 billion kilometers). Saturn's appearance changes with its seasons, which occur because its equator is tilted 27 degrees relative to the plane of its orbit around the Sun. This Saturn image was taken during summer in the planet's northern hemisphere. The amber colors of the planet come from summer smog-like hazes, produced in photochemical reactions driven by solar ultraviolet radiation. Below the haze lie clouds of ammonia ice crystals, as well as deeper, unseen lower-level clouds of ammonium hydrosulfide and water. #

Mystic Mountain. In 2010, Hubble peered deep into the Carina Nebula, 7,500 light-years from Earth, capturing this image of chaotic activity atop a pillar of gas and dust, three light-years tall, which is being eaten away by the brilliant light from nearby bright stars. The pillar is also being assaulted from within, as infant stars buried inside it fire off jets of gas that can be seen streaming from towering peaks. Streamers of hot ionized gas can be seen flowing off the ridges of the structure, and wispy veils of gas and dust, illuminated by starlight, float around its towering peaks. The denser parts of the pillar are resisting being eroded by radiation. #

It's Full of Stars. Messier 28, a globular cluster in the constellation of Sagittarius, is about 12 billion years old, and contains more than 50,000 stars. It was discovered by the French astronomer Charles Messier in 1764, and is now known to lie 18,000 light-years away from Earth. #

A Stellar Shell. This massive bubble in space is the result of gas that is being shocked by the expanding blast wave from a supernova. Called SNR 0509-67.5, the sphere is the visible remnant of a powerful stellar explosion in the Large Magellanic Cloud, a small galaxy about 160,000 light-years from Earth. Ripples in the shell's surface may be caused by either subtle variations in the density of the interstellar gas, or possibly driven from the interior by pieces of the ejecta. The bubble-shaped shroud of gas, observed by Hubble in on October of 2006, is 23 light-years across and is expanding at more than 11 million miles per hour (5,000 kilometers per second). #

A Galactic Warp. A Hubble view of of ESO 510-G1, an unusual galaxy seen edge-on, revealing remarkable details of its warped dusty disk and showing how colliding galaxies spawn the formation of new generations of stars. The dust and spiral arms of normal spiral galaxies, like our own Milky Way, appear flat when viewed edge-on. This galaxy lies about 150 million light-years away, in the constellation of Hydra. #

The Red Spider. Huge waves are sculpted in this two-lobed nebula some 3,000 light-years away in the constellation of Sagittarius. The Red Spider Nebula, a warm planetary nebula, harbors one of the hottest stars known and its powerful stellar winds generate waves 100 billion kilometers high. The waves are caused by supersonic shocks, formed when the local gas is compressed and heated in front of the rapidly expanding lobes. The atoms caught in the shock emit the spectacular radiation seen in this image. #

A Chance Alignment. A 2012 Hubble view of a pair of overlapping galaxies called NGC 3314. While the two galaxies look as if they are in the midst of a collision, this is in fact a trick of perspective: the just happen to be in alignment, from our vantage point—they are in fact separated by tens of millions of light years. #

The Lagoon Nebula. The entire nebula is an incredible 55 light-years wide and 20 light-years tall. This image shows only a small part of this turbulent star-formation region, which lies about 4,000 light-years away. This image, made by Hubble in 2018, shows a region full of intense activity, with fierce winds from hot stars, swirling chimneys of gas, and energetic star formation, embedded within a hazy labyrinth of gas and dust. #

A Hungry Monster. At the heart of the swirling arms of spiral galaxy NGC 3147 lies a malnourished black hole surrounded by a thin, compact disk of stars, gas, and dust that have been caught up in a gravitational maelstrom. The disk is so deeply embedded in the black hole's intense gravitational field, its light is being stretched and intensified. Hubble measured material whirling around the black hole moving at more than 10% of the speed of light—physical material moving at about 67 million mph (108 million kph), relative to the black hole. #

A Colorful Sea of Galaxies. We see here a tiny patch of our sky that had been previously studied by astronomers in a series of visible and near-infrared exposures taken from 2004 to 2009, known as the "Hubble Ultra Deep Field". In 2014, with the addition of ultraviolet light, they combined the full range of colors available to Hubble, stretching from ultraviolet to near-infrared light. The resulting image, a portion shown here, contains thousands of galaxies, extending back to within a few hundred million years of the Big Bang. #

A Celestial Smile. In the center of this image are two faint galaxies that seem to form a happy face (or possibly the head of a snowman)—you can make out two orange eyes and a white button nose. The two eyes are the galaxies SDSSCGB 8842.3 and SDSSCGB 8842.4 and the misleading smile lines are actually arcs caused by an effect known as strong gravitational lensing.  Massive structures in the Universe exert such a powerful gravitational pull that they can warp the spacetime around them and act as cosmic lenses which can magnify, distort and bend the light behind them. The arcs here show a special case of gravitational lensing, known as an Einstein Ring. #

An Enigmatic Cloud. Nebula IRAS 05437+2502 billows out among the bright stars and dark dust clouds that surround it in this striking Hubble image. It is located in the constellation of Taurus, close to the central plane of our Milky Way galaxy. Unlike many of Hubble’s targets, this object has not been studied in detail and its exact nature is unclear. The bright boomerang-shaped feature may be the resultof the interaction of a high velocity young star and the cloud, creating this unusually sharp-edged bright arc. #

Alone in the Void. In this image, only three nearby stars can be seen (the ones with 'diffraction spikes'), every other object is a distant galaxy. The bright spiral galaxy at center, named MCG+01-02-015, because of its lonely location, is called a 'void galaxy'. The vast majority of galaxies are strung out along galaxy filaments—thread-like formations drawn together by the influence of gravity into sinuous threads weaving through space. Between these filaments stretch shallow but immense voids with very little matter at all, except the occasional lonesome galaxy like this one. #

An Enormous Glowing Caterpillar. Scattered across the giant Carina nebula are numerous dense clumps of cosmic gas and dust called Bok globules, including this one, which resembles a huge caterpillar. First described by by astronomer Bart Bok, the globules are relatively small, dark, and cold regions made up of molecular hydrogen, carbon oxides, helium, and dust. The glowing edge of the caterpillar indicates that it is being photoionized by the hottest stars in the surrounding cluster. It has been hypothesized that stars may form inside these dusty cocoons. #

Rainbow Shells Around an Aging Star. The Egg Nebula, located 3,000 light-years away, offers astronomers a special look at the normally invisible dust shells swaddling an older star. These dust layers, extending over one-tenth of a light-year from the star, have an onionskin structure that forms concentric rings around the star. A thicker dust belt, running almost vertically through the image, blocks off light from the central star. Twin beams of light radiate from the hidden star and illuminate the pitch-black dust, like a shining flashlight in a smoky room. #

A Recent Family Photo. This image of Jupiter, made by Hubble on June 27, 2019, shows the giant planet's trademark Great Red Spot, and a more intense color palette in the clouds swirling in Jupiter's turbulent atmosphere than seen in previous years. The bands are created by differences in the thickness and height of the ammonia ice clouds. At the time this was taken, Jupiter was some 400 million miles away—yet it is so huge, with a diameter of 88,789 miles (142,984 km, or 11.2 times wider than Earth), that Hubble could still make this detailed portrait of our solar system neighbor. #

A Cosmic Lightsaber. The two narrow streams crossing the image are jets of energized gas, ejected from the poles of a young star in the the Orion B molecular cloud complex, which is located just over 1,350 light-years away. If the jets collide with the surrounding gas and dust they can clear vast spaces, and create curved shock waves, seen as knotted clumps called Herbig-Haro objects. #

A Close Encounter. This Hubble image from 2013 shows two interacting galaxies. NGC 2936 at top, once a standard spiral galaxy, and NGC 2937 below, a smaller elliptical galaxy. The pairing, known as Arp 142, bears a resemblance to a penguin guarding its egg. The gravitational chaos caused by the close interaction is twisting NGC 2936 and gradually tearing it apart. #

The Crab Nebula. A detailed view of this six-light-year-wide expanding remnant of a star's supernova explosion. The star exploded nearly 1,000 years ago, an event witnessed on Earth by Japanese and Chinese astronomers in 1054. #

Extremely Deep. Long Hubble observations of a tiny patch of sky near the constellation Fornax resulted in this, the "eXtreme Deep Field" image of thousands of galaxies both (relatively) near and far. Any bit of light you see in this image that does not have diffraction spikes is a galaxy, one of billions of "island universes" containing billions of stars each. And this image shows only a tiny bit of the night sky, an area a small fraction of the angular diameter of the full Moon. #

Spirals Within Spirals. Nearby galaxy NGC 1433 lies about 32 million light-years away. It is a type of very active spiral galaxy known as a Seyfert galaxy, with a bright, luminous center compared to our galaxy, the Milky Way. #

A Gigantic Pillar. Resembling a nightmarish beast rearing its head from a crimson sea, this celestial object called the Cone Nebula is actually just a pillar of gas and dust 2,500 light-years away. This picture shows the upper 2.5 light-years of the Cone—the entire pillar is seven light-years long. Radiation from hot, young stars (located beyond the top of the image) has slowly eroded the nebula over millions of years. #

The Antennae Galaxies. These galaxies, locked in a deadly embrace, were once normal, sedate spiral galaxies like the Milky Way. They have spent the past few hundred million years sparring with one another. This clash is so violent that stars have been ripped from their host galaxies to form a streaming arc between the two. This image shows clouds of gas in bright pink and red, surrounding the bright flashes of blue star-forming regions—some of which are partially obscured by dark patches of dust. Merry Christmas everyone! I hope you've enjoyed this year's Hubble Advent Calendar. And, here's wishing for a peaceful and joyous New Year. -Alan #