Mission planners have devised an unusual strategy for protecting orbiting spacecraft when Comet Siding Spring passes the Red Planet in October 2014.
Even on Io, a world known for spouting off, the titanic volcanic eruption seen on August 29, 2013, was among the most powerful ever recorded — unleashing an estimated 20 terawatts of energy.
Locally, spacetime is curved by the presence of massive objects. The total mass and energy density of the universe also has an effect on the overall curvature of space.
There was no “before the Big Bang"—the Big Bang created both time and space as we know it.
Dark matter is a mysterious type of matter that doesn't interact with any form of electromagnetic radiation, i.e., light. Although we’ve never detected dark matter directly, a large amount of evidence points to its existence.
Just how quickly is the universe expanding? Cosmologists attempt to answer this question in terms of the Hubble Constant, but the exact value of this constant is still a topic of debate.
Is the universe infinite, or just really, really big? How can we know? To answer these questions, we examine the possible shapes of the universe.
The media are all aflutter over the second of this summer's supermoon trio. But just how super is this moon, really?
Six years from now, there will be a new NASA robot heading to the Red Planet: the Mars 2020 rover. On July 31st mission planners unveiled the rover’s seven scientific instruments, which will pave the way for human exploration of Mars.
NASA's Fermi Space Telescope recently spotted a pulsar in a rare transitional phase as it devours the matter of its companion star.
Scientists have confirmed that the soft X-ray glow permeating the sky has two sources: one inside the solar system, one outside.
Barring the Sun, the closest star to Earth is a triple system called Alpha Centauri, which is over four light years away.
Because black holes severely warp the fabric of spacetime, they have a curious effect on the passage of time as seen by an outside observer.
Black holes are singularities: points of infinitely small volume with infinite density. However, the amount of a mass concentrated in a black hole varies, and the mass determines how wide the black hole's sphere of influence is.
Different types of black holes form through different processes.
The concept of a black hole was first contrived in by John Michell 1783. For a long time, many notable scientists, including Albert Einstein, believed black holes were merely theoretical. However, in the last century, astronomers have gathered a good deal of observational evidence for the existence of black holes.
A black hole is a region of space where the force of gravity is so strong that the escape velocity exceeds the speed of light.
The Big Bang marked the beginning of the universe's expansion from a singularity — a single point that was infinitely small, infinitely hot, and infinitely dense. Cosmologists have designated several distinct eras for the universe's evolution from the first moments after the Big Bang to a billion years later.
Cosmologists have invoked the concept of dark energy to explain the accelerated expansion of the universe, but the nature of dark energy remains one of the most pressing questions facing modern cosmology.
The universe began as a singularity that started expanding in the Big Bang. But the Big Bang was no regular explosion. Rather, space itself expanded, so there is no center of the entire universe. The observable universe, on the other hand, is a different story.
Astronomers determine the number of galaxies in the universe by counting up the number visible in a tiny portion of the sky, and then accounting for all the regions of the observable universe. A 2013 study estimates that there are 225 billion galaxies in the observable universe.
Determining the age of the universe requires a knowledge of the universe's expansion rate, as well as its density and composition. Cosmologists currently set the age of the universe at about 13.77 billion years.
During the latter half of the 20th century, cosmologists narrowed the universe’s fate to three possibilities, and they all depend on its density.
The Rosetta spacecraft is closing in on Comet 67P/C-G, providing astronomers with an ever more detailed view of its structure. Judging by the latest photos, it actually has two components and is shaped like… a rubber ducky?
In 1930, the International Astronomical Union (IAU) divided the sky into 88 constellations. Each constellation is defined by an imaginary boundary on the sky and named after a classical star pattern within those boundaries. So when we say a star is “in” a particular constellation, we mean it lies within the IAU-defined boundaries of...