Hubble in the News
An interstellar comet, a black hole, and a “heavy metal” exoplanet made headlines in 2019.
NASA’s Hubble Space Telescope, which has made almost 1.5 million observations of over 46,000 astronomical objects since its 1990 launch, continues to upend our understanding of the universe. Read the top news stories released in 2019.
First Confirmed Interstellar Comet
This year, an object called comet 2I/Borisov was detected falling past our sun by a Crimean amateur astronomer. It is only the second known object to enter our solar system coming from elsewhere in our Milky Way galaxy, based on its speed and trajectory. Hubble took a series of snapshots as the comet streaked along at 110,000 miles per hour, revealing a central concentration of dust around an unseen nucleus. The comet was 260 million miles from Earth when Hubble took the photo.
Comet 2I/Borisov looks a lot like the traditional comets found inside our solar system, which sublimate ices and cast off dust as they are warmed by the Sun. The wandering comet provides invaluable clues to the chemical composition, structure, and dust characteristics of planetary building blocks presumably forged in an alien star system. By the middle of 2020, the comet will streak past Jupiter’s distance of 500 million miles on its way back into interstellar space where it will drift for untold millions of years before skirting close to another star system. Keep reading about comet 2I/Borisov.
Uncovering a ‘Heavy Metal’ Exoplanet
Hubble observations revealed magnesium and iron gas streaming from WASP-121b, a planet that resides about 900 light-years from Earth. The observations represent the first time that so-called heavy metals—elements heavier than hydrogen and helium—have been spotted escaping from a hot Jupiter, a large, gaseous exoplanet very close to its star.
The intense radiation heats the planet’s upper atmosphere to a blazing 4,600 degrees Fahrenheit. Apparently, the lower atmosphere is still so hot that iron and magnesium remain in gaseous form and stream to the upper atmosphere, where they escape into space on the coattails of hydrogen and helium gas. Normally, hot Jupiter-sized planets are still cool enough inside to condense heavier elements such as magnesium and iron into clouds.
The sizzling planet is so close to its star that it is on the cusp of being ripped apart by the star’s gravity. Its tight orbit around the star means that the planet is probably football-shaped due to gravitational tidal forces. Unravel the forces at work.
Mystery of the Universe’s Expansion Rate Widens with Two New Hubble Data Sets
The expansion rate of the universe, called the Hubble constant after its discoverer Edwin Hubble, is a long-sought value because it yields clues to the origin, age, evolution, and future fate of our universe. For decades, astronomers have worked to precisely measure the Hubble constant.
Before the Hubble Space Telescope was launched in 1990, the universe’s age was thought to lie between 10 and 20 billion years, based on different estimates of the Hubble constant. Not long after Hubble’s launch, astronomers greatly refined the Hubble constant value to a precision of 10 percent. This was possible because the Hubble telescope excels at finding and measuring variable stars as milepost markers.
This spring, astronomers using new Hubble measurements of stars that pulse at regular cycles reduced the uncertainty in their Hubble constant value to 2.4 percent, bringing the estimate to 74 kilometers per second per megaparsec. The ultimate goal is to refine measurements to 1 percent accuracy. However, their data remain at odds with the value derived from observations of light from the early universe’s expansion known as the Cosmic Microwave Background, collected by the European Space Agency’s Planck satellite, which predicts the Hubble constant to be 67 kilometers per second per megaparsec. This discrepancy suggests that there may be unknown underlying physics in the properties of the universe. Read about the expanding universe.
Identifying a Black Hole Disk That Shouldn’t Exist
Astronomers using Hubble have found an unexpected thin disk of material furiously whirling around a supermassive black hole at the heart of spiral galaxy NGC 3147. Based on current astronomical theories, the disk shouldn’t be there: Models predict that an accretion disk forms when ample amounts of gas are trapped by a black hole’s strong gravitational pull. This infalling matter emits lots of light, producing a brilliant beacon called a quasar in the case of the most well-fed black holes. It is theorized that once less material is pulled into the disk, it begins to break down, becomes fainter, and changes structure. Through the observations of NGC 3147, researchers found instead gas in motion producing features that can be explained only as being produced by material rotating in a thin disk very close to the black hole. The team hopes to use Hubble to hunt for other very compact disks around “low-wattage” black holes in similar active galaxies to learn more about the mechanics at work. Learn about the eating habits of black holes.
Astronomers Assemble Wide View of the Evolving Universe
This image, known as the Hubble Legacy Field, contains roughly 265,000 galaxies that stretch back through 13.3 billion years, presenting a wide portrait of the distant universe. This deep-sky mosaic, created from nearly 7,500 individual exposures, shows how galaxies change over time, building themselves up to become the giant galaxies seen in the nearby universe. This image also includes observations taken by several Hubble deep-field surveys, including the eXtreme Deep Field (XDF), the deepest view of the universe. These observations combine ultraviolet, visible, and near-infrared light, and provide high-resolution measurements of the galaxies, which will enable a wide swath of extragalactic study. The Hubble Legacy Field, along with the individual exposures that make up the new view, is available through STScI’s Mikulski Archive for Space Telescopes (MAST). Stare in awe at the Hubble Legacy Field.
A Spun-up Asteroid Comes Apart
Images from Hubble show two narrow, comet-like tails of dusty debris streaming from the asteroid (6478) Gault. Each tail represents an episode in which the asteroid gently shed its material—evidence that Gault is beginning to come apart. Discovered in 1988, the 2.5-mile-wide (4-kilometer-wide) asteroid has been observed repeatedly, but the debris tails are the first evidence of disintegration. Gault is located 214 million miles (344 million kilometers) from the Sun. Of the roughly 800,000 known asteroids between Mars and Jupiter, astronomers estimate that this type of event in the asteroid belt is rare, occurring roughly once a year. Watching an asteroid become unglued gives astronomers the opportunity to study the makeup of these space rocks without sending a spacecraft to sample them. Learn more about asteroid (6478) Gault.
Planets Shine in New Hubble Images
Astronomers use Hubble annually to survey the major outer planets in our solar system. These are dynamic worlds with ever-changing turbulent atmospheres, some driven by seasonal changes. The latest view of Neptune (top left) shows a dark storm at top center. These storms are ephemeral. Three previous storms seen by Hubble since the early 1990s have come and gone.
The snapshot of Uranus (top right) reveals a vast bright cloud cap across its north pole. Scientists believe this feature is a result of Uranus’ extreme tilt, which means that during the planet’s summer the Sun shines almost directly onto the north pole and never sets.
This year’s view of Jupiter (bottom left) shows its trademark Great Red Spot and a more intense color palette in the clouds swirling in its turbulent atmosphere than seen in previous years, important clues to ongoing processes in its atmosphere.
Hubble’s latest image of Saturn (bottom right) shows that a large storm visible in last year’s image in the north polar region has vanished. The planet’s banded structure also reveals subtle color changes. Read about more about Hubble’s 2019 observations of Neptune and Uranus, Jupiter, and Saturn.
Tiny Neptune Moon May Have Broken from Larger Moon
Astronomers call it “the moon that shouldn’t be there.” After several years of analysis, a team of planetary scientists using Hubble has provided an explanation for a moon discovered around Neptune with Hubble in 2013. The tiny moon, named Hippocamp, is unusually close to a much larger Neptunian moon called Proteus. Normally, a moon like Proteus should have gravitationally swept aside or swallowed the smaller moon while clearing out its orbital path. So why does the tiny moon exist? Hippocamp is likely a chipped-off piece of the larger moon that resulted from a collision with a comet billions of years ago. It is only 20 miles (about 34 kilometers) across and 1/1000th the mass of Proteus, which is 260 miles (about 418 kilometers) across. Learn what we know about Hippocamp.
Uncovering the Brightest Quasar in the Early Universe
Astronomers using Hubble have discovered the brightest object ever seen at a time when the universe was less than one billion years old: A quasar, the core of a galaxy with a supermassive black hole ravenously eating material surrounding it, which is 12.8 billion light-years away. Cataloged as J043947.08+163415.7, the quasar shines with light equivalent to 600 trillion Suns. An immense amount of energy is emitted as its central black hole consumes material around it. The detection provides a rare opportunity to study a zoomed-in image of how such black holes accompanied star formation in the very early universe and influenced the assembly of galaxies. This quasar could hold the record of being the brightest in the early universe for some time, making it a unique object for follow-up studies. Explore what we know about the quasar.