The Gaia satellite has spotted an enormous 'ghost' galaxy lurking on the outskirts of the Milky Way. An international team of astronomers, including from the University of Cambridge, discovered the massive object when trawling through data from the European Space Agency's Gaia satellite. The object, named Antlia 2 (or Ant 2), has avoided detection until now thanks to its extremely low density as well as a perfectly-chosen hiding place, behind the shroud of the Milky Way's disc. The researchers have published their results online today.

According to the most widely-accepted cosmological theory, the first stars in our Universe formed roughly 150 to 1 billion years after the Big Bang. Over time, these stars began to come together to form globular clusters, which slowly coalesced to form the first galaxies – including our very own Milky Way. For some time, astronomers have held that this process began for our galaxy some 13.51 billion years ago.

Some of the winning images from the Royal Observatory Greenwich's annual competition.

Astronomers are building instruments that can characterize the many alien worlds the Kepler spacecraft revealed—and look for signs of life.

As BepiColombo heads to Mercury — a long-neglected planet — Nature looks at which planets attract scientific missions, and why. Last week, the BepiColombo spacecraft successfully began its seven-year journey to Mercury — only the third-ever mission sent to the planet. The day before, scientists said that NASA’s next Mars rover — intended to be first to gather and return rock samples to Earth — should visit as many places on the red planet as possible.

An astro-photographer has captured the 'once in a lifetime' moment a meteor exploded before disintegrating into the night sky in Shorpshire. The scene, which has been recorded very few times on camera, was caught during an Orionid meteor shower. Orionid meteors occur every Autumn when the Earth is passing through the stream of debris left by Halley's Comet.

New research shows a pattern of exoplanet sizes and spacing around other stars unlike what we see in our own system

There's a telescope that can see thick rings of dust in distant star systems. These rings are huge — wide enough in some cases to encircle most or all the planets in our solar system. And they're the birthplaces of exoplanets. Understanding how they work could teach us about how the planets in our own solar system formed.

Chia Min Tan, a Ph.D. Student based at the Jodrell Bank Centre for Astrophysics in Manchester's School of Physics and Astronomy, was part of an international team including fellow astronomers at Manchester, ASTRON and the University of Amsterdam. The team carried out the observations using the Low-Frequency Array (LOFAR), whose core is located in the Netherlands. Their findings were published in the Astrophysical Journal.

For the second time this year, the five brightest planets can be seen at the same time. You can catch them by looking towards the western sky after sunset. The planets will form a line rising up from the horizon. Mercury and Venus are low to the west, with bright Jupiter shining just above. Higher up in the northwestern sky is Saturn, and completing the set of five is the red planet Mars, high overhead.

NASA’s Hubble telescope might still be snapping out of a gyroscope-induced funk, but the space agency’s other powerful space-gazing lenses are still working just fine. In a new post, NASA’s Jet Propulsion Laboratory is showcasing a truly stunning image captured by the Spitzer Space Telescope, which peered into the Milky Way to spot the Cat’s Paw Nebula and the big space bubbles it keeps blowing.

Looking around at Earth's neighbors, it's fair to say we're on the most livable planet in our solar system. (Lift your game, Mars.) But while Earth seems unique in being able to support life, it's probably not the only planet in the universe with that distinction. There are other planets, known as exoplanets, which are rocky orbs like ours and which orbit their own stars in other solar systems. If those planets exist in the so-called Goldilocks zone -- the orbital distance around their star that makes them not too hot and not too cold...

The tally of potentially habitable alien planets may have to be revised downward a bit. To date, NASA's prolific Kepler space telescope has discovered about 30 roughly Earth-size exoplanets in their host stars' "habitable zone" — the range of orbital distances at which liquid water can likely exist on a world's surface. Or so researchers had thought. New observations by the European Space Agency's (ESA) Gaia spacecraft suggest that the actual number is probably significantly smaller — perhaps between two and 12, NASA officials said today (Oct. 26). [Photos: Gaia Spacecraft to Map Milky Way Galaxy]

Titan, Saturn’s largest moon, is enveloped in a thick, hazy atmosphere. One new research collaboration has identified a chemical mechanism that could help to explain how the moon's haze formed. “Both space probes and land-based instruments have identified the chemical composition of the major constituents of the haze,” said Musahid Ahmed, a scientist in Berkeley Lab’s Chemical Sciences Division and co-leader of the study. “However, how some of heavier particles are formed from the lighter gases is still an open question.”

New observations by two Arizona State University astronomers using the Hubble Space Telescope have caught a red dwarf star in a violent outburst, or superflare. The blast of radiation was more powerful than any such outburst ever detected from the Sun, and would likely affect the habiltability of any planets orbitiing it.

This weekend, go outside and look up in the dark hours before dawn to witness the annual Orionid meteor shower, which will hit its peak overnight on October 21-22. You may have seen a few stray meteors zooming across the sky, leftover Draconids whose peak passed earlier this month or leftover meteors from the South Taurid shower that’s still ongoing. But this week, and more specifically this weekend, the Orionid meteors will be easy to spot.

A team of astronomers using the latest set of data from ESA's Gaia mission to look for high-velocity stars being kicked out of the Milky Way were surprised to find stars instead sprinting inwards -- perhaps from another galaxy.

Astronomers have announced the possible discovery of the first known moon outside our Solar System. This "exomoon" is not like any in our cosmic neighbourhood: it's the size of Neptune and orbits a planet the size of Jupiter - but with 10 times the mass. The object was spotted in data from Nasa's Kepler spacecraft, and later observed using the Hubble telescope. Astronomers David Kipping and Alex Teachey have published their results in Science Advances journal.

After 10 years of observations, scientists have confirmed a two-year cycle in the gamma-ray brightness of a blazar, or a galaxy with a supermassive black hole that consumes mass and produces high-energy jets as a result. Blazars are the most energetic and luminous objects that we have identified so far in the known universe.

The Kepler roller-coaster ride continues. NASA's low-on-fuel Kepler space telescope, which has discovered more than 2,650 alien planets to date, has awoken from yet another slumber and begun making science observations again, agency officials announced today (Sept. 5). The $600 million Kepler mission launched in March 2009, tasked with determining how common Earth-like planets are around the galaxy. The spacecraft initially studied more than 150,000 stars simultaneously, looking for tiny brightness dips caused by the passage of orbiting planets across these stars' faces. [Gallery: A World of Kepler Planets]

To be housed in a building 22 stories high, on a plateau of the Atacama Desert of Chile, the Giant Magellan Telescope will be the largest optical telescope ever built.

Pluto wrongly lost its planet status, say, scientists, suggesting that the icy dwarf should be reclassified as a planetary body. In 2006, the International Astronomical Union (IAU), a global group of astronomy experts, established a definition of a planet that required it to "clear" its orbit, or in other words, be the largest gravitational force in its orbit.

A giant ring of black holes has been discovered 300 million light-years away, offering new clues about what happens when galaxies collide. Using NASA's Chandra X-ray Observatory, astronomers detected a very bright source of X-rays that is likely fueled by either a ring of stellar-mass black holes or neutron stars — the small, dense corpses left after stellar explosions, — according to a new study.

The universe is filled with billions of massive celestial objects, from stars to planets to comets to asteroids. But what happens when lines start to blur between these classifications, and we just can’t place an object in any major category? Well, brown dwarfs know this better than anyone. They’re far too massive to be planets, but not massive enough for hydrogen atoms to fuse in their cores and become stars.

Newfound exoplanet orbits a star identified with the famed science officer from "Star Trek."

A space rock dubbed a “death comet” that eerily resembles a skull is expected to hurtle past Earth shortly after Halloween. Officially known as asteroid 2015 TB145, the comet is expected to fly past Earth at a distance of 25 million miles on Nov. 11, more than three years after it first zoomed past Earth at a much closer distance in October 2015.

For one brief shining moment after the 2015 detection of gravitational waves from colliding black holes, astronomers held out hope that the universe’s mysterious dark matter might consist of a plenitude of black holes sprinkled throughout the universe. UC Berkeley physicists have dashed those hopes.

We live 26,000 light-years from the center of the Milky Way. That’s a rounding error by cosmological standards, but still — it’s far. When the light now reaching Earth from the galactic center first took flight, people were crossing the Bering Strait land bridge, hunting woolly mammoths along the way.

A new mathematical model suggests that signs of extraterrestrial intelligence could be common, for all we know—we’ve barely begun investigating the vastness where they might lie. The Fermi paradox is the contrast between the likelihood of life existing elsewhere in the universe and the lack if evidence for it. This is a significant conundrum. On the one hand, there is a strong sense that the conditions on Earth that led to the emergence of life cannot be unique. This makes it seem likely that life must be common.

Jupiter’s largest moon, Ganymede, is an icy world that astronomers believe hides a liquid ocean beneath its surface. That fractured surface, which jumbles old and new features together, has long hinted at a complex history astronomers have sought to understand. Now, a new study to be published in print November 15 in Icarus shows that Ganymede has undergone periods of tectonic processes much like those seen on Earth, bringing to light some of the moon’s tumultuous past.

The Drake equation is one of astronomy’s most famous attempts to answer the question: Are we alone? A single equation lets astronomers estimate how many advanced civilizations capable of contacting us might be out there. Here's how it works. The Drake equation is one of astronomy’s most famous attempts to answer the question: Are we alone? It asks not just about any life, but the top shelf stuff: intelligent life with the ability to communicate with beings outside their planet.

Nasa has found an entire solar system with as many planets as our own. The discovery of a new planet around the Kepler-90 star, which looks like our own sun, means the distant solar system has a total of eight known planets. And those planets look like those in our own neighbourhood: rocky planets orbit close to the star, with gas giants further away.

We’ve all heard the old expression “Once in a blue moon” and it means something happens very rarely. The last time an actual blue moon total lunar eclipse happened was over 150 ye…

Enhanced color image from Juno

Researchers have identified a new and previously overlooked process for air penetration that may explain the powerful explosion of the Chelyabinsk meteoroid.