Some of the Hubble Space Telescope's most stunning images reveal galaxies in distress. Many of them are in the throes of a gravitational encounter with another galaxy. The photos show perfect pinwheel patterns stretched and pulled into irregular shapes. Streamers of gas and dust flow from galaxies into space. And in this chaos, batches of young, blue stars glow like tree lights, fueled by the dust and gas kicked up by the galactic encounter. For some galaxies, the powerful meeting with a passing galaxy will eventually end in mergers.

But hidden from view deep inside the dusty cores of these... Read more

In a cosmic tug-of-war between two dwarf galaxies orbiting the Milky Way, only NASA’s Hubble Space Telescope can see who’s winning. The players are the Large and Small Magellanic Clouds, and as they gravitationally tug at each other, one of them has pulled out a huge amount of gas from its companion. This shredded and fragmented gas, called the Leading Arm, is being devoured by the Milky Way and feeding new star birth in our galaxy. But which dwarf galaxy is doing the pulling, and whose gas is now being feasted upon? Scientists used Hubble’s ultraviolet vision to chemically analyze the gas in the... Read more

Supermassive black holes, weighing millions of times as much as our Sun, are gatherers not hunters. Embedded in the hearts of galaxies, they will lie dormant for a long time until the next meal happens to come along.

The team of astronomers using observations from the Hubble Space Telescope, the Chandra X-ray Observatory, and as well as the W.M. Keck Observatory in Mauna Kea, Hawaii, and the Apache Point Observatory (APO) near Sunspot, New Mexico, zeroed in on a flickering black hole.

A black hole in the center of galaxy SDSS J1354+1327, located about 800 million light-years away, appears to... Read more

Voices reverberating off mountains and the sound of footsteps bouncing off walls are examples of an echo. Echoes happen when sound waves ricochet off surfaces and return to the listener.

Space has its own version of an echo. It’s not made with sound but with light, and occurs when light bounces off dust clouds.

The Hubble telescope has just captured one of these cosmic echoes, called a “light echo,” in the nearby starburst galaxy M82, located 11.4 million light-years away. A movie assembled from more than two years’ worth of Hubble images reveals an expanding shell of light from a supernova... Read more

Normally, hefty black holes anchor the centers of galaxies. So researchers were surprised to discover a supermassive black hole speeding through the galactic suburbs. Black holes cannot be observed directly, but they are the energy source at the heart of quasars — intense, compact gushers of radiation that can outshine an entire galaxy. NASA's Hubble Space Telescope made the discovery by finding a bright quasar located far from the center of the host galaxy.

Researchers estimate that it took the equivalent energy of 100 million supernovas exploding simultaneously to jettison the black hole. What... Read more

About 6 million years ago, when our very remote ancestors began to evolve away from chimpanzees, our Milky Way galaxy's hefty black hole was enjoying a sumptuous feast. It gulped down a huge clump of interstellar hydrogen.

Now, eons later, we see the result of the black hole feast. The black hole "burped" hot plasma that is now towering far above and below the plane of our galaxy. These invisible bubbles, weighing the equivalent of millions of suns, are called the Fermi Bubbles. Their energetic gamma-ray glow was first discovered in 2010 by NASA's Fermi Gamma-ray Space Telescope. (Enrico Fermi was... Read more

The old adage "what goes up must come down" even applies to an immense cloud of hydrogen gas outside our Milky Way galaxy. First discovered in the 1960s, the comet-shaped cloud is 11,000 light-years long and 2,500 light-years across. If the cloud could be seen in visible light, it would span the sky with an apparent diameter 30 times greater than the size of the full moon. The cloud, which is invisible at optical wavelengths, is plummeting toward our galaxy at nearly 700,000 miles per hour. Hubble was used to measure the chemical composition of the cloud as a means of assessing where it came from.... Read more

Quasars are the light fantastic. These brilliant cores of active galaxies blaze with the radiance of a hundred billion stars compressed into a region of space not much larger than our solar system. Supermassive black holes, with millions or billions of times the mass of our sun, are the only imaginable powerhouse behind these tsunamis of raw energy.

Hubble Space Telescope astronomers set their sights on the nearest quasar to Earth, Markarian 231, located 581 million light-years away. Black holes – even supermassive ones – are too compact to be resolved by any present-day telescope. So, astronomers... Read more

Astronomers have long wondered how the universe's largest elliptical galaxies continue making stars long after their peak years of star birth. By combining data from NASA's Hubble Space Telescope with observations from a suite of ground-based and space telescopes, two independent teams have uncovered a unique process to explain how this star birth continues. The teams found that that the galaxy's central black hole, jets, and newborn stars are all parts of a self-regulating cycle. In that cycle, jets shooting out of the galaxy's center heat a halo of surrounding gas, controlling the rate at which it... Read more

Quasars are the light fantastic. They are the brightest beacons in the universe, blazing across space with the intrinsic brightness of one trillion suns. Yet the objects are not vast galaxies, but they appear as pinpoint sources in the biggest telescopes of today – hence the term "quasar" for quasi-stellar object. Discovered in the 1960s, it took more than two decades of research to come to the conclusion that quasars are produced by the gusher of energy coming from over-fed supermassive black holes inside the cores of very distant galaxies. And, most quasars bloomed into a brief existence 12 billion... Read more