Nasa Image of the Day

Nebula RCW49

One of the most prolific birthing grounds in our Milky Way galaxy, a nebula called RCW 49, is exposed in superb detail for the first time in this new image from NASA's Spitzer Space Telescope. Located 13,700 light-years away in the southern constellation Centaurus, RCW 49 is a dark and dusty stellar nursery that houses more than 2,200 stars.

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The Sky Tonight Astronomy News
NASA's Hubble Finds Water Vapor on Habitable-Zone Exoplanet for the First Time
Fri, 13 Sep 2019 11:00:00 EDTHubble Image

To date, approximately 4,000 planets have been found orbiting other stars. The majority are extremely hostile to any chances for life: with exotic atmospheres, wide temperature extremes, and oddball orbits. Astronomers have now made an important step toward the ultimate goal of finding an exoplanet with an atmosphere more like Earth's, and having moderate temperatures. Water vapor has been identified in the atmosphere of a planet called K2-18b, located 110 light-years away. And, where there's water there could be clouds and rain. The planet is also at the right distance from its star to have a temperate climate where the water doesn't evaporate or freeze. But don't go looking for real estate yet. The planet is in a category not found in our solar system. It is larger than Earth but smaller than Neptune. It might have a rocky surface, but it is more likely a giant ball of liquid and gas, like Neptune. Hundreds of known exoplanets fall into this mass range. So, it's important for astronomers to characterize the worlds and assess the chances for supporting life as we know it.



Cheops mission update - Read more >
Fri, 13 Sep 2019 12:06:00 +0200


Watch a media briefing on our Cheops exoplanet mission Monday 12:15–13:15 CEST live from the European Planetary Science Congress



Saturn's Rings Shine in New Hubble Portrait
Thu, 12 Sep 2019 10:00:00 EDTHubble Image

Saturn is so beautiful that astronomers cannot resist using the Hubble Space Telescope to take yearly snapshots of the ringed world when it is at its closest distance to Earth.

These images, however, are more than just beauty shots. They reveal a planet with a turbulent, dynamic atmosphere. This year's Hubble offering, for example, shows that a large storm visible in the 2018 Hubble image in the north polar region has vanished. Smaller storms pop into view like popcorn kernels popping in a microwave oven before disappearing just as quickly. Even the planet's banded structure reveals subtle changes in color.

But the latest image shows plenty that hasn't changed. The mysterious six-sided pattern, called the "hexagon," still exists on the north pole. Caused by a high-speed jet stream, the hexagon was first discovered in 1981 by NASA's Voyager 1 spacecraft.

Saturn's signature rings are still as stunning as ever. The image reveals that the ring system is tilted toward Earth, giving viewers a magnificent look at the bright, icy structure. Hubble resolves numerous ringlets and the fainter inner rings.

This image reveals an unprecedented clarity only seen previously in snapshots taken by NASA spacecraft visiting the distant planet. Astronomers will continue their yearly monitoring of the planet to track shifting weather patterns and identify other changes. The second in the yearly series, this image is part of the Outer Planets Atmospheres Legacy (OPAL) project. OPAL is helping scientists understand the atmospheric dynamics and evolution of our solar system's gas giant planets.



Exciting exoplanet - Read more >
Thu, 12 Sep 2019 12:29:00 +0200


Hubble finds water vapour on habitable-zone exoplanet for the first time, paving the way for future discoveries by the James Webb Space Telescope and the Ariel mission



Unexpected periodic flares may shed light on black hole accretion - Read more >
Wed, 11 Sep 2019 19:00:00 +0200


ESA’s X-ray space telescope XMM-Newton has detected never-before-seen periodic flares of X-ray radiation coming from a distant galaxy that could help explain some enigmatic behaviours of active black holes. 




Hubble Explores the Formation and Evolution of Star Clusters in the Large Magellanic Cloud
Mon, 09 Sep 2019 11:00:00 EDTHubble Image

Like batches of cookies, stars are born together in groups. These star clusters, containing as many as 1 million members, evolve over time largely through a gravitational pinball where more massive stars are segregated from lower mass stars. Heavy stars tend to progressively sink toward the central region of the star cluster, while low-mass stars can escape from the system.

For the first time, the Hubble Space Telescope has been used to measure the effects of this dynamical aging on star clusters. They are all located 160,000 light-years from Earth in a satellite galaxy, the Large Magellanic Cloud (LMC). The diminutive galaxy is an ideal target because it hosts a selection of easily observed star clusters covering a wide range of ages.

Francesco Ferraro of the University of Bologna in Italy and his team used Hubble to observe five aging LMC star clusters — all born at about the same time but with different sizes — and succeeded in ranking them in terms of the level of dynamical evolution, which affects their shape.



Magnetic wonder - Read more >
Mon, 09 Sep 2019 11:10:00 +0200


Space Science Image of the Week: Plotting the surprising changes in Mercury’s magnetic history



Gaia untangles the starry strings of the Milky Way - Read more >
Wed, 28 Aug 2019 10:00:00 +0200


Rather than leaving home young, as expected, stellar ‘siblings’ prefer to stick together in long-lasting, string-like groups, finds a new study of data from ESA’s Gaia spacecraft.




ExoMars rover ready for environment testing - Read more >
Tue, 27 Aug 2019 15:00:00 +0200


The Rosalind Franklin ExoMars rover has completed its construction activities in the UK and will now depart to France for testing under the conditions of the Red Planet’s environment.




Jupiter mission takes first images of destination – from Earth - Read more >
Thu, 22 Aug 2019 11:00:00 +0200


As part of preparations for the launch of ESA’s Jupiter Icy Moons Explorer, its navigation camera has been given a unique test: imaging its destination from Earth.




All instruments onboard Rosalind Franklin rover - Read more >
Tue, 20 Aug 2019 15:00:00 +0200


The full suite of scientific instruments, including cameras that will give us our eyes on Mars, the drill that will retrieve pristine soil samples from below the surface, and the onboard laboratory that will seek out signs of life are all installed on the ExoMars rover.




ExoMars parachute testing continues - Read more >
Mon, 12 Aug 2019 15:00:00 +0200


As the second ExoMars mission, comprising a rover and surface science platform, progresses towards launch next year, teams continue to troubleshoot the parachute design following an unsuccessful high-altitude drop test last week.




Hubble's New Portrait of Jupiter
Thu, 08 Aug 2019 10:00:00 EDTHubble Image

Jupiter is the king of the solar system, more massive than all of the other solar-system planets combined. Although astronomers have been observing the gas-giant planet for hundreds of years, it still remains a mysterious world.

Astronomers don't have definitive answers, for example, of why cloud bands and storms change colors, or why storms shrink in size. The most prominent long-lasting feature, the Great Red Spot, has been downsizing since the 1800s. However, the giant storm is still large enough to swallow Earth.

The Red Spot is anchored in a roiling atmosphere that is powered by heat welling up from the monster planet's deep interior, which drives a turbulent atmosphere. In contrast, sunlight powers Earth's atmosphere. From Jupiter, however, the Sun is much fainter because the planet is much farther away from it. Jupiter's upper atmosphere is a riot of colorful clouds, contained in bands that whisk along at different wind speeds and in alternating directions. Dynamic features such as cyclones and anticyclones (high-pressure storms that rotate counterclockwise in the southern hemisphere) abound.

Attempting to understand the forces driving Jupiter's atmosphere is like trying to predict the pattern cream will make when it is poured into a hot cup of coffee. Researchers are hoping that Hubble's yearly monitoring of the planet—as an interplanetary weatherman—will reveal the shifting behavior of Jupiter's clouds. Hubble images should help unravel many of the planet's outstanding puzzles. This new Hubble image is part of that yearly study, called the Outer Planets Atmospheres Legacy program, or OPAL.



Dark meets light on Mars - Read more >
Thu, 08 Aug 2019 11:00:00 +0200


ESA’s Mars Express has captured the cosmic contrast of Terra Cimmeria, a region in the southern highlands of Mars marked by impact craters, water-carved valleys, and sand and dust in numerous chocolate and caramel hues.




Hubble Uncovers a 'Heavy Metal' Exoplanet Shaped Like a Football
Thu, 01 Aug 2019 10:00:00 EDTHubble Image

The scorching hot exoplanet WASP-121b represents a new twist on the phrase "heavy metal."

There are no loud electric guitar riffs, characteristic of heavy metal music, streaming into space. What is escaping the planet is iron and magnesium gas, dubbed heavy metals, because they are heavier than lightweight hydrogen and helium. The observations by the Hubble Space Telescope represent the first time heavy metal gas has been detected floating away from an exoplanet.

A scorching planet, WASP-121b orbits precariously close to a star that is even hotter than our Sun. 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.

The sizzling planet is also so close to its star that it is on the cusp of being ripped apart by the star's intense pull. This hugging distance means that the planet is stretched into a football shape due to gravitational tidal forces.



Cheops passes final review before shipment to launch site - Read more >
Mon, 29 Jul 2019 14:00:00 +0200


The Characterising Exoplanet Satellite, Cheops, has successfully passed the final analysis review for its launch on a Soyuz rocket from Europe’s Spaceport in Kourou, French Guiana.




Astronomers spy Europa blocking distant star – thanks to Gaia - Read more >
Thu, 25 Jul 2019 10:00:00 +0200


On 31 March 2017, Jupiter’s moon Europa passed in front of a background star – a rare event that was captured for the first time by ground-based telescopes thanks to data provided by ESA’s Gaia spacecraft.




Gaia starts mapping our galaxy’s bar - Read more >
Tue, 16 Jul 2019 15:00:00 +0200


The first direct measurement of the bar-shaped collection of stars at the centre of our Milky Way galaxy has been made by combining data from ESA’s Gaia mission with complementary observations from ground- and space-based telescopes.




New Hubble Constant Measurement Adds to Mystery of Universe's Expansion Rate
Tue, 16 Jul 2019 08:00:00 EDTHubble Image

In 1924, American astronomer Edwin Hubble announced that he discovered galaxies outside of our Milky Way by using the powerful new Hooker telescope perched above Los Angeles. By measuring the distances to these galaxies, he realized the farther away a galaxy is, the faster it appears to be receding from us. This was incontrovertible evidence the universe is uniformly expanding in all directions. For nearly a decade Albert Einstein refused to accept the observational evidence. His theory of general relativity described a static universe. But this could only be accomplished by invoking a "cosmological constant," which he described as repulsive property of space that would counterbalance the pull of gravity and prevent the universe from imploding. The expansion rate is the basis of the Hubble constant. It is a sought-after value because it yields clues to the origin, age, evolution, and future fate of our universe.

For nearly the past century astronomers have worked meticulously 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. Improving this value was one of the biggest justifications for building the Hubble telescope. This paid off in the early 1990s when a team led by Wendy Freedman of the University of Chicago greatly refined the Hubble constant value to a precision of 10%. This was possible because the Hubble telescope is so sharp at finding and measuring Cepheid variable stars as milepost markers — just as Edwin Hubble did 70 years earlier.

But astronomers strive for ever greater precision, and this requires further refining yardsticks for measuring vast intergalactic distances of billions of light-years. Freedman's latest research looks at aging red giant stars in nearby galaxies. They are also milepost markers because they all reach the same peak brightness at a critical stage of their late evolution. This can be used to calculate distances.

Freedman's research is one of several recent studies that point to a nagging discrepancy between the universe's modern expansion rate and predictions based on the universe as it was more than 13 billion years ago, as measured by the European Space Agency's Planck satellite. This latest measurement offers new evidence suggesting that there may be something fundamentally flawed in the current model of the universe.



Gaia’s biggest operation since launch - Read more >
Mon, 15 Jul 2019 16:00:00 +0200


On Tuesday 16 July, teams at ESA’s mission control will perform an ‘orbit change manoeuvre’ on the Gaia space observatory – the biggest operation since the spacecraft was launched in 2013.




Hubble Uncovers Black Hole Disk that Shouldn't Exist
Thu, 11 Jul 2019 10:00:00 EDTHubble Image

Astronomers are always tickled when they find something they didn't expect to be there. Peering deep into the heart of the majestic spiral galaxy NGC 3147, researchers uncovered a swirling gas disk precariously close to a black hole weighing about 250 million times the mass of our Sun. The surprise is that they thought the black hole was so malnourished, it shouldn’t have such a structure around it. It's basically a "Mini-Me" version of more powerful disks seen in very active galaxies.

What's especially intriguing is that the disk is so deeply embedded in the black hole's intense gravitational field, its light is being stretched and intensified by the black hole's powerful grasp. It's a unique, real-world demonstration of Einstein's laws of relativity, formulated a century ago.

Hubble clocked material whirling around the black hole as moving at more than 10% of the speed of light. And, the gas astronomers measured is so entrenched in the gravitational well that light is struggling to climb out, and therefore appears stretched to redder wavelengths.



Dust storms swirl at the north pole of Mars - Read more >
Thu, 04 Jul 2019 14:00:00 +0200


ESA’s Mars Express has been keeping an eye on local and regional dust storms brewing at the north pole of the Red Planet over the last month, watching as they disperse towards the equator.




STScI to Design Science Operations for New Panoramic Space Telescope
Tue, 02 Jul 2019 17:00:00 EDTHubble Image

NASA has awarded a contract to the Space Telescope Science Institute (STScI) in Baltimore, Maryland, for the Science Operations Center (SOC) of the Wide Field Infrared Survey Telescope (WFIRST) mission. WFIRST is a NASA observatory designed to settle essential questions in a wide-range of science areas, including dark energy and dark matter, and planets outside our solar system.



Atmosphere of Mid-Size Planet Revealed by Hubble and Spitzer
Tue, 02 Jul 2019 11:00:00 EDTHubble Image

Our solar system contains two major classes of planets. Earth is a rocky terrestrial planet, as are Mercury, Venus, and Mars. At about the distance of the asteroid belt, there is a "frost line" where space is so cold more volatile material, like water, can remain frozen. Out here live the gas giants–Jupiter, Saturn, Uranus, and Neptune–which have bulked up on hydrogen and helium and other volatiles.

Astronomers are curious about a new class of planet not found in the Solar System. Weighing in at 12.6 Earth masses the planet is more massive than Earth, but less massive than Neptune (hence, intermediate between the rocky and gaseous planets in the Solar System). What's more, the planet, GJ 3470 b, is so close to its red dwarf star that it completes one orbit in just three days! As odd as it seems, planets in this mass range are likely the most abundant throughout the galaxy, based on surveys by NASA's Kepler space telescope. But they are not found in our own solar system.

Astronomers enlisted the combined multi-wavelength capabilities of NASA's Hubble and Spitzer space telescopes to assemble for the first time a "fingerprint" of the chemical composition of GJ 3470 b's atmosphere, which turns out to be mostly hydrogen and helium, and surprisingly, largely lacking heavier elements. One possible explanation is that the planet formed as a 10-Earth-mass rocky core that then accumulated hydrogen very close to its star, rather than migrated in which is the conventional wisdom for star-hugging planets.



Hubble Captures the Galaxy's Biggest Ongoing Stellar Fireworks Show
Mon, 01 Jul 2019 10:00:00 EDTHubble Image

In the mid-1800s, mariners sailing the southern seas navigated at night by a brilliant star in the constellation Carina. The star, named Eta Carinae, was the second brightest star in the sky for more than a decade. Those mariners could hardly have imagined that by the mid-1860s the brilliant orb would no longer be visible. Eta Carinae was enveloped by a cloud of dust ejected during a violent outburst.

Stars don't normally play vanishing acts unless they are undergoing rapid and violent activity. Observations by the Hubble Space Telescope and other observatories have helped astronomers piece together the story of this unique star's petulant behavior. During part of its adult life, Eta Carinae has undergone a series of eruptions, becoming extremely bright during each episode, before fading away. One explanation for the monster star's antics is that the convulsions were caused by a complex interplay of as many as three stars, all gravitationally bound in one system. The most massive member – weighing in at 150 times our Sun's mass – swallowed one of the stars. This violent event ignited the massive outburst of the mid-1800s. Evidence for that event, dubbed the Great Eruption, lies in the huge, expanding bipolar lobes of hot gas surrounding the system.

Because of Eta Carinae's violent history, astronomers have kept watch over its activities. Although Hubble has monitored the volatile superstar for 25 years, it still is uncovering new revelations. Using Hubble to map the ultraviolet-light glow of magnesium embedded in warm gas, astronomers were surprised to discover the gas in places they had not seen it before. The newly revealed gas is important for understanding how the eruption began, because it represents the fast and energetic ejection of material that may have been expelled by the star shortly before the expulsion of the bipolar bubbles.

One of the most massive known stars in the Milky Way galaxy, Eta Carinae is destined to finally meet its end by exploding as a supernova.



ExoMars 2020: progress and challenges - Read more >
Fri, 28 Jun 2019 15:00:00 +0200


The full parachute system that will help deliver the ExoMars rover and a surface science platform to the martian surface has completed a full-scale high-altitude deployment sequence test, although unexpected damage to the main parachutes occurred.




A chaos found only on Mars - Read more >
Thu, 27 Jun 2019 11:00:00 +0200


 The cracked, uneven, jumbled landscape seen in this image from ESA’s Mars Express forms an intriguing type of terrain that cannot be found on Earth: chaotic terrain.




ESA’s new mission to intercept a comet - Read more >
Wed, 19 Jun 2019 15:20:00 +0200


 ‘Comet Interceptor’ has been selected as ESA’s new fast-class mission in its Cosmic Vision Programme. Comprising three spacecraft, it will be the first to visit a truly pristine comet or other interstellar object that is only just starting its journey into the inner Solar System.




Table Salt Compound Spotted on Europa
Wed, 12 Jun 2019 15:00:00 EDTHubble Image

Finding common table salt — sodium chloride — on the surface of a moon is more than just a scientific curiosity when that moon is Europa, a potential abode of life.

If the salt came from the briny subsurface ocean of Europa, a satellite of Jupiter, that ocean may chemically resemble Earth's oceans more than previously thought. Because Europa's solid, icy crust is geologically young it has been suspected that whatever salts exist on the surface may come from the ocean below, which might host microorganisms.

Using visible-light spectral analysis, planetary scientists at Caltech and NASA's Jet Propulsion Laboratory discovered that the yellow color visible on portions of the surface of Europa is sodium chloride. They reached this conclusion with spectroscopic data from NASA's Hubble Space Telescope. Researchers were able to identify a distinct absorption in the visible spectrum which matches how salt would look when irradiated by the Sun.

Tara Regio is the yellowish area to left of center, in this NASA Galileo image of Europa’s surface. This region of geologic chaos is the area researchers identified an abundance of sodium chloride.

The finding was published in Science Advances on June 12.



A Pair of Fledgling Planets Directly Seen Growing Around a Young Star
Mon, 03 Jun 2019 11:00:00 EDTHubble Image

In order to grow to Jupiter size or larger, a gas giant planet must slurp large quantities of hydrogen and other gases from the disk in which it forms. Astronomers have looked for evidence of this process, but direct observations are challenging because planets become lost in the glare of their star. A team has succeeded in making ground-based observations of two planets accreting matter from a disk. It represents only the second multi-planet system to be directly imaged.



Galaxy Blazes with New Stars Born from Close Encounter
Thu, 16 May 2019 10:00:00 EDTHubble Image

One doesn't need a Ph.D. in astrophysics to recognize there is something odd-looking about this otherwise beautiful galaxy, NCG 4485. Like the Batman character Two-Face, one side looks normal, but the other side looks contorted with a firestorm of star formation going on. Why the colorful asymmetry in an island star city many thousands of light-years across? The clue is off the edge of the photo. It's another galaxy, NGC 4490, that swept by NGC 4485 millions of years ago. The gravitational taffy pull between the two galaxies compressed interstellar gas to trigger a flurry of new star birth as seen in the abundance of young blue stars and pinkish nebulas. So, out of a near-collision between two galaxies comes stellar renewal and birth. It's a trademark of our compulsive universe where even things as big as galaxies can go bump in the night.



Hubble Astronomers Assemble Wide View of the Evolving Universe
Thu, 02 May 2019 10:00:00 EDTHubble Image

How far is far? And, how do you know when you get there? In 1995, astronomers decided to use the Hubble Space Telescope to conduct a bold and daring experiment to address this puzzle. For 10 consecutive days, Hubble stared at one tiny, seemingly empty patch of sky for 1 million seconds.

The gamble of precious telescope time paid off. Hubble captured the feeble glow of myriad never-before-seen galaxies. Many of the galaxies are so far away it has taken billions of years for their light to reach us. Therefore, the view is like looking down a "time corridor," where galaxies can be seen as they looked billions of years ago. Hubble became astronomy's ultimate time machine.

The resulting landmark image is called the Hubble Deep Field. At the time, the image won the gold medal for being the farthest peek into the universe ever made. Its stunning success encouraged astronomers to pursue a series of Hubble deep-field surveys. The succeeding surveys uncovered more galaxies at greater distance from Earth, thanks to new cameras installed on Hubble during astronaut servicing missions. The cameras increased the telescope's power to look even deeper into the universe.

These surveys provided astronomers with a huge scrapbook of images, showing how, following the big bang, galaxies built themselves up over time to become the large, majestic assemblages seen today in the nearby universe.

Among the most notable deep-field surveys are the Great Observatories Origins Deep Survey (GOODS), in 2003; the Hubble Ultra Deep Field (HUDF), in 2004; and the eXtreme Deep Field (XDF), in 2012.

Now, astronomers are releasing a new deep-field image by weaving together exposures from several of these previous galaxy "fishing expeditions." Their efforts have produced the largest, most comprehensive “history book” of galaxies in the universe. The snapshot, a combination of nearly 7,500 separate Hubble exposures, represents 16 years' worth of observations. The ambitious endeavor is called the Hubble Legacy Field. The new view contains about 30 times as many galaxies as in the HUDF. The wavelength range stretches from ultraviolet to near-infrared light, capturing all the features of galaxy assembly over time.

The image mosaic presents a wide portrait of the distant universe and contains roughly 265,000 galaxies. They stretch back through 13.3 billion years of time to just 500 million years after the universe's birth in the big bang.



Mystery of the Universe's Expansion Rate Widens with New Hubble Data
Thu, 25 Apr 2019 10:00:00 EDTHubble Image

There is something wrong with our universe. Or, more specifically, it is outpacing all expectations for its present rate of expansion.

Something is amiss in astronomers' efforts to measure the past and predict the present, according to a discrepancy between the two main techniques for measuring the universe's expansion rate – a key to understanding its history and physical parameters.

The inconsistency is between the Hubble Space Telescope measurements of today's expansion rate of the universe (by looking at stellar milepost markers) and the expansion rate as measured by the European Space Agency's Planck satellite. Planck observes the conditions of the early universe just 380,000 years after the big bang.

For years, astronomers have been assuming this discrepancy would go away due to some instrumental or observational fluke. Instead, as Hubble astronomers continue to "tighten the bolts" on the accuracy of their measurements, the discordant values remain stubbornly at odds.

The chances of the disagreement being just a fluke have skyrocketed from 1 in 3,000 to 1 in 100,000.

Theorists must find an explanation for the disparity that could rattle ideas about the very underpinnings of the universe.



Hubble Celebrates 29th Anniversary with a Colorful Look at the Southern Crab Nebula
Thu, 18 Apr 2019 10:00:00 EDTHubble Image

This Hubble image shows the results of two stellar companions in a gravitational waltz, several thousand light-years from Earth in the southern constellation Centaurus. The stellar duo, consisting of a red giant and white dwarf, are too close together to see individually in this view. But the consequences of their whirling about each other are two vast shells of gas expanding into space like a runaway hot air balloon. Both stars are embedded in a flat disk of hot material that constricts the outflowing gas so that it only escapes away above and below the stars. This apparently happens in episodes because the nebula has two distinct nested hourglass-shaped structures. The bubbles of gas and dust appear brightest at the edges, giving the illusion of crab legs. The rich colors correspond to glowing hydrogen, sulfur, nitrogen, and oxygen. This image was taken to celebrate Hubble's 29th anniversary since its launch on April 24, 1990.



NASA Awards 2019 Postdoctoral Fellowships
Thu, 04 Apr 2019 10:00:00 EDTHubble Image

NASA has selected 24 new Fellows for its prestigious NASA Hubble Fellowship Program (NHFP). The program enables outstanding postdoctoral scientists to pursue independent research in any area of NASA Astrophysics, using theory, observation, experimentation, or instrument development. Each fellowship provides the awardee up to three years of support.



Hubble Watches Spun-up Asteroid Coming Apart
Thu, 28 Mar 2019 10:00:00 EDTHubble Image

Astronomers once thought asteroids were boring, wayward space rocks that simply orbit around the Sun. These objects were dramatically presented only in science fiction movies.

But recent observations show that asteroids are anything but dull. In reality they are dynamic, active worlds that can ultimately disintegrate due to the long-term subtle effects of sunlight, which can slowly spin them up until they begin to shed material.

Several telescopes, including NASA's Hubble Space Telescope, have caught the gradual self-destruction of the asteroid (6478) Gault. Images from Hubble show two narrow, comet-like tails of dusty debris streaming from the diminutive asteroid.

For Gault, a mass of rubble a few miles across, mere sunlight set the stage for its gradual demise. The force of sunlight, in concert with Gault's own asymmetrical shape, speeded up the asteroid's rotation over a period of more than 100 million years. The estimated spin-up rate is 1 second every 10,000 years.

Today, the asteroid is rotating once every two hours, a speed so fast that it can no longer hold its surface material. The slightest disturbance — perhaps the impact of a pebble, or just a failure of the stressed material — may have set off a collapse. The dust left the asteroid's surface in gentle, short bursts, perhaps due to landslides lasting anywhere from a few hours to a few days. The particles are drifting away from Gault's surface at the speed of a strolling human. The gentle process is like scattering flour into the air, where wind — or sunlight, in the case of Gault — stretches the debris into a long streamer.

Astronomers will monitor the asteroid for future events. About 800,000 known asteroids reside between Mars and Jupiter, and they may fly apart at the rate of roughly one per year.


This Month's Sky Map
This Month's Sky Map

Take a look at this month's Sky Map to help you explore the wonders of the night sky!

Ideal for all sky watchers including beginners to astronomy.

The Sky Map will help you identify planets, bright stars, constellations and nebulae!
Printable version available too!


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