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Recent Podcast
A Quick Look at W51
A Quick Look at W51
Because of its relative proximity, the giant molecular cloud W51 provides astronomers with an excellent opportunity to study how stars are forming in our Milky Way galaxy. (2017-07-12)
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Animations & Video: Featured Image Tours
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1. Tour of Galaxy Clusters
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Since its discovery almost two decades ago, dark energy has remained one of the biggest mysteries in science. Astronomers know that dark energy is responsible for the current accelerating expansion of the Universe, but they are still trying to determine just what it is.

A new study tries to tackle the questions surrounding dark energy by examining properties of X-ray emission from galaxy clusters. Galaxy clusters are the largest structures in the Universe held together by gravity and they contain enormous amounts of hot gas that glow in X-ray light. Researchers know that galaxy clusters possess another interesting quality: the more massive ones are simply scaled up versions of the smaller ones -- like Russian dolls that fit inside one another.

Astronomers can take advantage of this fact to use galaxy clusters as cosmic distance markers. Since dark energy is pushing the Universe apart, the different distances of these galaxy clusters reveals clues about the nature of dark energy itself.

The latest research, looking at over 300 galaxy clusters, shows that dark energy does not appear to change over billions of years. This supports the idea that dark energy is what Einstein called the cosmological constant, which is the equivalent to the energy of empty space. While this new study is very exciting, there is still much to be learned before we know exactly what dark energy is, how it has affected the Universe in the past, and what it might do in the future.
[Runtime: 02:32]
(NASA/CXC/A. Hobart)

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2. Tour of GJ 3253
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Despite appearing as a steady yellow disk in our sky, the Sun is actually an incredibly active ball of superheated gas. Sometimes the Sun has storms that launch from its surface and send energy and particles into the Solar System. On Earth, these solar storms can generate auroras, damage satellites and power grids, and potentially harm astronauts in orbit.

Therefore, many scientists are working hard to better understand what causes the Sun to act as it does. They do know that the Sun's magnetic fields are largely responsible for producing its behavior, but there are still many details that remain mysterious.

By studying the X-ray emission of four stars with lower masses than the Sun, a pair of astronomers may have made an important discovery. They found that these lower-mass stars have magnetic fields that are similar in strength to stars like the Sun. This is surprising because the Sun and Sun-like stars have different regions within them where energy flows differently. Astronomers have thought the boundary between these different regions would contribute to the strength of the magnetic fields. If stars without such a boundary - like those in this latest study - have magnetic fields of similar strength, then this theory may need to be re-examined.
[Runtime: 02:23]
(NASA/CXC/A. Hobart)

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3. Tour of GRB 140903A
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Gamma-ray bursts are some of the most powerful explosions in the Universe. As their name implies, these events produce spectacular outbursts in gamma rays and often in other types of light over time such as X-rays and optical light. By studying the details of these different types of light, astronomers try to piece together exactly what is going on with these cosmic blasts.

On September 3, 2014, instruments aboard the Swift telescope picked up a gamma-ray burst, which was dubbed GRB 140903A. About three weeks later, a team of researchers used Chandra to study the afterglow of the event in X-rays.

By combining the Chandra observations with optical data from ground-based telescopes, astronomers have determined that GRB 140903A was the merger of two neutron stars in a galaxy about 3.9 billion light years from Earth. In addition, they found evidence that the gamma-ray burst produced pencil-thin beams of radiation. Astronomers were only able to detect this event because the jets generated by the blast were pointed toward Earth.

What does this mean? The implication is that if some or all mergers like this produce these narrow beams, then astronomers may be missing a vast majority of them because they do not fall along our line of sight. This is interesting to many scientists who study these kinds of events. And since neutron star mergers are thought to be sources of gravitational waves, scientists using LIGO and other future observatories will need to know this information in order to hone their searches.
[Runtime: 02:59]
(NASA/CXC/A. Hobart)

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4. Tour of IC 2497
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Citizen science projects have done some remarkable things in recent years and those in astronomy are no exception. One of the early success stories of the Galaxy Zoo citizen science project was the discovery of an unusual object in 2007. This object was found by Hanny van Arkel who, at the time, was a school teacher in the Netherlands. Today, the object is known as "Hanny's Voorwerp," which means "Hanny's object" in Dutch.

Professional astronomers have also taken an interest in Hanny's Voorwerp. This unusually-shaped cloud of gas, which also has another nickname of the "green blob," is located only about 200,000 light years from the galaxy IC 2497. While this sounds like a huge distance, it is actually very close in cosmic terms. Because of that, Hanny's Voorwerp is affected by what goes on in IC 2497, in particular by the behavior of the giant black hole at its center. In fact, the green blob gets its color because oxygen atoms in the gas cloud have been excited by the incoming ultraviolet and X-ray radiation from regions close to the black hole.

Even though astronomers suspect this black hole was a so-called quasar in the past, recent Chandra observations indicate that it has since faded. So far, Hanny's Voorwerp shows no sign of dimming, but with the 200,000 light year separation, astronomers in the upcoming millennia might just see the lights in the green blob start to flicker off.

New observations with Chandra suggest that the black hole is still producing large amounts of energy even though it is no longer generating intense radiation as a quasar. The X-ray data suggest that jets powered by the black hole have blown a large bubble in surrounding gas. This shows that giant black holes can have a big effect on their environments.
[Runtime: 3.00]
(NASA/CXC/A. Hobart)

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5. Tour of Jupiter
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Many people have heard of auroras, also called the 'northern lights', which are spectacular light shows that occur near Earth's poles. What might not be as well known is that other planets in our Solar System also experience auroras. Jupiter is one of them.

A new study using data from NASA's Chandra X-ray Observatory has shown that storms from the Sun are triggering auroras in X-ray light that are some eight times brighter than normal, covering a large area of Jupiter's surface. These Jovian auroras are hundreds of times more energetic than the auroras we have here on Earth.

These latest results represent the first time that Jupiter's auroras have been studied in X-ray light when a giant storm from the Sun arrives at the planet. The Sun constantly ejects streams of particles into space in the solar wind. Sometimes, giant storms erupt and the winds become much stronger. These events compress Jupiter's magnetosphere, the region of space controlled by Jupiter's magnetic field, shifting its boundary with the solar wind inward by more than a million miles. This new study found that the interaction at the boundary triggers the X-rays in Jupiter's auroras, which cover an area bigger than the surface of the Earth.

The discovery comes as NASA's Juno spacecraft nears Jupiter for the start of its mission this summer. Launched in 2011, Juno aims to unlock the secrets of Jupiter's origin, helping scientists to better understand how the solar system, including Earth, formed. As part of the mission, Juno will investigate Jupiter's relationship with the Sun and the solar wind by studying its magnetic field, magnetosphere and aurora. To complement the work being done by Juno, the researchers on this latest study plan to find out how the X-rays form by collecting more data with Chandra as well as with ESA's XMM-Newton.
[Runtime: 02:08]
(NASA/CXC/A. Hobart)

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6. Tour of NGC 5128
QuicktimeMPEG With closed-captions (at YouTube)

Astronomers have found a pair of extraordinary objects that dramatically burst in X-rays. This discovery, made using data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton observatory, may represent a new class of explosive events.

The mysterious sources flare up and become about a hundred times brighter in X-rays in less than a minute, before returning to the original X-ray levels after about an hour. One of the sources, located near and presumably associated with the galaxy NGC 4636 at a distance of 47 million light years, was observed to flare once. Five flares were detected from the other source, which is located near the galaxy NGC 5128 at a distance of 12 million light years.

What could these objects be? Probably not magnetars, which are young neutron stars with powerful magnetic fields. Magnetars are also known to have giant X-ray flares, but they are different from these newly discovered objects in a few different ways including how long they flare and where they are found.

While the nature of these flares is unknown, researchers have begun to search for answers. One idea is that the flares represent episodes when matter being pulled away from a companion star falls rapidly onto a black hole or neutron star. This could happen when the companion makes its closest approach to the compact object in an eccentric orbit. Another explanation could involve matter falling onto an intermediate-mass black hole, with a mass of about 800 times that of the Sun for one source and 80 times that of the Sun for the other.

These new flaring objects will likely keep both observational and theoretical astrophysicists busy for quite some time. Using telescopes like Chandra and XMM-Newton, they undoubtedly hope to come up with more answers soon.
[Runtime: 03:04]
(NASA/CXC/UA/J.Irwin et al.)

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7. Tour of NGC 6357
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Although there are no seasons in space, this cosmic vista invokes thoughts of a frosty winter landscape. It is, in fact, a region called NGC 6357 where radiation from hot, young stars is energizing the cooler gas in the cloud that surrounds them.

Located about 5,500 light years from Earth, NGC 6357 is actually a "cluster of clusters" containing at least three clusters of young stars, including many hot, massive, luminous stars. X-ray data from Chandra and ROSAT reveal hundreds of point sources, which are the young stars in NGC 6357, as well as diffuse X-ray emission from hot gas. There are bubbles, or cavities, that have been created by radiation and material blowing away from the surfaces of massive stars, plus supernova explosions.

Researchers use Chandra to study NGC 6357 and similar objects because young stars are bright in X-rays. Also, X-rays can penetrate the shrouds of gas and dust surrounding these infant stars, allowing astronomers to see details of star birth that would be otherwise missed.
[Runtime: 02:08]
(NASA/CXC/A. Hobart)

Related Chandra Images:

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8. Tour of Pluto
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

During the summer of 2015, scientists and the public alike were treated to a flood of images and discoveries about Pluto as the New Horizon spacecraft made an unprecedented flyby of the dwarf planet. The discoveries about Pluto didn't stop with the initial results that were released. Rather, the New Horizons spacecraft will provide scientists with years worth of discoveries of this cold and distant world.

While New Horizons is accomplishing much on its own, there is even more science to be uncovered when other telescopes join the effort. This is the case for X-ray observations of Pluto made by the Chandra X-ray Observatory as New Horizons made its approach and then flew by Pluto.

The Chandra data show that Pluto has surprisingly high amounts of X-ray emission for a cold and rocky planet that has no known significant magnetic field. While X-rays have been detected elsewhere in the Solar System -- including comets, Mars, Saturn, and Jupiter - it appears that Pluto's X-rays are not generated in exactly the same way as these other objects. Rather, the researchers suggest that the X-rays from Pluto come from the interaction of gases in Pluto's atmosphere and the stream of particles from the Sun known as the solar wind. Scientists hope to learn more about Pluto and other objects in the outermost regions of our Solar System with future observations.
[Runtime: 02:19]
(NASA/CXC/A. Hobart)

Related Chandra Images:

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9. Tour of RCW 103
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

When stars have more than about 8 times as much mass as the Sun, they end their lives in a spectacular explosion called a supernova. The outer layers of the star are hurtled out into space at millions of miles per hour, leaving a debris field of gas and dust. Where the star once was located, a small, incredibly dense object called a neutron star is often found. While only 10 miles or so across, the tightly packed neutrons in such a star contain more mass than the entire Sun.

The supernova remnant called RCW 103 is a by-product of one of these explosions and the neutron star it left behind, known as 1E 1613, is proving to be particularly interesting. For years, astronomers have known that 1E 1613 shows a regular brightening and dimming in its X-rays that repeats about every six and a half hours. It could be a neutron star that is rotating much more slowly than other neutron stars, or it could be a faster-spinning neutron star that has a normal star as a companion.

New data from four high-energy telescopes, Chandra, Swift, NuSTAR and XMM-Newton, have shown that the unusually slow spin is the correct explanation and that.1E 1613 has the properties of a magnetar. Magnetars are neutron stars that possess enormously powerful magnetic fields, trillions of times greater than that on the Sun.

While it is still unclear why 1E 1613 is spinning so slowly, scientists do have some ideas. One leading scenario is that debris from the exploded star has fallen back onto magnetic field lines around the spinning neutron star, causing it to spin more slowly with time. Searches are currently being made for other very slowly spinning magnetars to study this idea in more detail.
[Runtime: 03:06]
(NASA/CXC/A. Hobart)

Related Chandra Images:

Click for high-resolution animation
10. Tour of SPT 0346-52
QuicktimeMPEG Audio Only With closed-captions (at YouTube)

Astronomers have used NASA's Chandra X-ray Observatory and other telescopes to show that a very distant galaxy is undergoing an extraordinary boom of stellar construction. The galaxy is 12.7 billion light years from Earth, which means it is at a critical stage in the evolution of galaxies about a billion years after the Big Bang.

After astronomers discovered the galaxy, known as SPT 0346-52, with the South Pole Telescope, they observed it with several space and other ground-based telescopes. Data from the Atacama Large Millimeter/submillimeter Array revealed this galaxy was giving off tremendous amounts of infrared light.

This excess infrared light could be explaining by a huge burst of star formation. However, there was another possibility: What if the infrared emission was instead caused by a rapidly growing supermassive black hole at the galaxy's center? Gas falling towards the black hole would become much hotter and brighter, causing surrounding dust and gas to glow in infrared light.

To explore this possibility, researchers used Chandra and the Australia Telescope Compact Array, a radio telescope. If there was a massive, growing black hole in the middle of SPT0346-52, it should give off enough X-rays and radio waves for these telescopes to detect.

The result was that neither Chandra nor the Australia Telescope Compact Array saw emission coming from SPT0346-52. The absence of X-rays and radio waves let astronomers rule out a growing black hole being responsible for most of the bright infrared light.

Instead of this galaxy containing a gorging black hole, astronomers know it is shining brightly with the light from newborn stars. This gives scientists information about how galaxies and the stars within them evolve during some of the earliest times in the Universe.
[Runtime: 03:08]
(NASA/CXC/A. Hobart)

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