Bright star surrounded by shell of gas and dust

An exoplanet on its second atmosphere, the expected return of a supernova, and Jupiter’s great red spot top the headlines in 2021.

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NASA's Hubble Space Telescope, which has made 1.5 million observations of over 49,000 astronomical objects since its 1990 launch, continues to expand what we know about the universe. Read the top news stories released in 2021.


Hubble Observations Help Researchers Calculate Age and Site of Supernova Blast

Red, green, and blue ribbons of glowing gaseous clumps make up the supernova remnant

Using Hubble, astronomers analyzed remnants from a violent stellar explosion to determine exactly when and where it lit up in the night sky. Hubble observations, taken 10 years apart, of supernova remnant 1E 0102 allowed astronomers to retrace the explosion and calculate the cloud's expansion rate.

While previous studies have provided an estimated age of this supernova to be between 2,000 and 1,000 years old, this year's new analysis is more precise. Instead of comparing data taken from two different instruments aboard Hubble, the telescope's longevity has allowed researchers to compare data taken from the same instrument—Hubble's Advanced Camera for Surveys.

Astronomers measured the velocities of 45 ejecta clumps, or knots, flung from the supernova blast. Using the two separate sets of data, researchers traced the knots' motion backward until the ejecta coalesced at one point, identifying the explosion site. Once that was known, they could calculate how long it took the speedy knots to travel from the explosion center to their current location. Their analysis reveals that the light from the exploded star reached Earth 1,700 years ago. Dive into the investigation.

Concentration of Small Black Holes Uncovered by Hubble

Image of globular star cluster NGC 6397 containing blue stars, red giant stars, and a number of small white objects

Within the glittering, blinding swarm of thousands of stars known as globular cluster NGC 6397, Hubble researchers expected to find a black hole—more specifically, an intermediate-mass black hole tugging at the stars inside the cluster. However, Hubble data revealed that there is not just one hefty black hole, but a swarm of smaller black holes—a mini-cluster in the core of the globular star cluster.

In search of the elusive hidden mass, Hubble researchers analyzed the positions and velocities of the cluster's stars to determine the distribution of its total mass. The more mass in a location, the faster the stars travel around it. Precise Hubble observations recorded over several years tracked the stars' tiny proper motions (their apparent motions on the sky), which allowed researchers to determine their true velocities within the cluster. Conclusions indicated that the orbits of the stars are close to random throughout the globular cluster, rather than systematically circular or elongated.

This Hubble discovery is the first to provide both the mass and the extent of what appears to be a collection of mostly black holes in the center of a globular cluster. Learn more about this unusual finding.

Hubble Solves Mystery of Monster Star's Dimming

Hubble view of the nebula surrounding the star. Middle: closeup Hubble view of the region around the star. Right: Illustration

A colossal star 300,000 times brighter than our Sun, VY Canis Majoris, has dimmed so much it's no longer visible to the naked eye, but Hubble still zeroed in and learned more about what's caused it to appear to fade. Hubble data suggests VY Canis Majoris is dimming for the same reason as the star Betelgeuse, just on a more extreme scale. Researchers found the hypergiant star is casting off material—undergoing violent ejections—and the resulting expelled shrouds of dust have blocked the light from the star. Eventually, the star may explode as a supernova, or may simply collapse and form a black hole. Explore more discoveries involving the red hypergiant.

Hubble Tracks Down Fast Radio Bursts to Galaxies' Spiral Arms

Locations of fast radio bursts circled with a dotted white line in two galaxies

Tracking down where fast radio bursts come from has been a sticking point for astronomers for many years. Only about 15 of the 1,000 spotted in the last two decades have been traced to their home galaxies. Locating where these blasts are coming from, and in particular what galaxies they originate from, is important in determining what kinds of astronomical events trigger such intense flashes of energy. High-resolution data from Hubble has now allowed researchers to track down five fast radio bursts to the spiral arms of five distant galaxies. With Hubble, astronomers could also discern the host-galaxy properties, such as mass and star-formation rate, as well as probe exactly what's happening around the fast radio bursts. Uncover more about these fast radio bursts.

Hubble Detects Distant Exoplanet on Its Second Atmosphere

Illustration of exoplanet GJ 1132 b

Hubble was the first telescope to directly detect an exoplanet's atmosphere, so it's only fitting that this year it became the first to detect an exoplanet's second atmosphere, shown in an artist's illustration. The exoplanet in question, GJ 1132 b, is thought to have originally started as a sub-Neptune, with an atmosphere of mostly hydrogen and helium. New evidence gathered by Hubble suggests that radiation from the young, hot star it orbits blasted away the primordial haze, stripping it to a bare core. At that point, astronomers suggest volcanic activity on the exoplanet's surface regenerated, and continues to actively replenish, a new atmosphere—a toxic mix of hydrogen, methane, and hydrogen cyanide. Keep reading about this strange world.

Double Quasars in Merging Galaxy Caught by Hubble

Double quasars compass and scale image

Hubble's crisp resolution has long made headlines for finding the needle in a haystack and this year it discovered not one, but two of the brightest proverbial needles. Hubble captured two pairs of quasars (active supermassive black holes) that existed 10 billion years ago at the cores of two merging galaxies. The objects are too close to be resolved separately by ground-based telescopes. They are only about 10,000 light-years apart. It's the first time double quasars at the start of galaxy formation have been recorded. Astronomers say each double quasar will eventually merge, spiraling together and forming a massive, single black hole. Dive into the details of these rare pairs.

Hubble Spots Disappearing Supernova Blast, Rerun Expected in 2037

Left frame shows three images of a supernova in cluster MACS J0138. The multiply imaged supernova disappears in right image

With Hubble looking on, a monstrous galaxy cluster magnified the light from a far-off supernova, splitting it into three images. That's not the end of it, though. Astronomers expect an encore in 2037. The distant supernova, named Requiem, appears in the giant galaxy cluster MACS J0138. The cluster is so massive that its powerful gravity bends and magnifies the light from the supernova, located in a galaxy far behind it. The three lensed supernova images, seen as tiny dots captured in a single Hubble snapshot, represent light from the explosive aftermath. The dots vary in brightness and color, which signify three different phases of the fading blast as it cooled over time. Researchers used a computer model of the cluster to lay out the different paths the supernova light is taking through dark matter. Expand your knowledge of this distant phenomenon.

Water Vapor on Two of Jupiter's Moons Detected by Hubble

Two panel image comparing Ganymede in ultraviolet wavelengths

Spectroscopic analysis using Hubble instruments can provide researchers a "fingerprint" of a celestial object's temperature, chemical composition, and motion. The moons orbiting gas giant Jupiter are among the most intriguing targets within our solar system for astronomers to study using this method. This year, new and archival data from Hubble allowed researchers to track the presence of water vapor on both Ganymede and Europa, a groundbreaking first for Ganymede and an intriguing new chapter to Europa's story.

With Ganymede, the largest moon in the solar system, Hubble researchers used analysis of ultraviolet aurora images to confirm that water vapor is present due to thermal escape from the moon's icy surface—not the ocean roughly 100 miles below. Unlike Ganymede, astronomers have found water vapor on Europa before, but this year's study revealed the presence of persistent water vapor in one hemisphere. Read more about the discoveries on Ganymede and Europa.

Hubble Clocks Increasing Wind Speeds in Jupiter's Great Red Spot

Side by side of Jupiter's Great Red Spot and a rotation velocity map

Hubble's longevity and vantage point from space has given astronomers a unique chance to monitor the dynamic atmospheres of our solar system's outer planets over a long period of time. Not only can Hubble track changes to the gas giants' weather patterns on a larger scale, but its resolution can give researchers the chance to zero in on particular storms. The latest "weather report" is about Jupiter's Great Red Spot, where the winds in the outermost "lane" of the storm are accelerating. The average wind speed just within the boundaries of the storm, known as a high-speed ring, has increased by up to 8 percent from 2009 to 2020. In contrast, the winds near the red spot's innermost region are moving significantly more slowly. Read about winds in the "fast lane."


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