Since ancient times, astronomers have looked up at the night sky and seen the Andromeda galaxy. As the closest galaxy to our own, scientists have been able to observe and scrutinize this giant spiral galaxy for millennia. By the 20th century, astronomers realized that Andromeda was the Milky Way’s sister galaxy and was moving towards us. In 4.5 billion years, it will even merge with our own to form a supergalaxy.

Just sending a rocket into orbit is expensive. Getting to Mars would cost even more. That's why NASA is looking into cheaper options like atomic rockets.

The biggest black holes in the Universe are growing faster than the rate of stars being formed in their galaxies, according to two new studies using data from NASA’s Chandra X-ray Observatory and other telescopes.

Our Milky Way and the Andromeda galaxy – two giant galaxies in our local patch of the universe – are heading for an immense collision with each other in only a few billion years’ time. So which will dominate in this intergalactic tussle?

Beauty, grace, mystery — this magnificent spiral galaxy has all the qualities of a perfect galactic Valentine. Captured by the NASA/ESA Hubble Space Telescope, the galaxy NGC 3344 presents itself face-on, allowing astronomers a detailed look at its intricate and elegant structure. And Hubble’s ability to observe objects over a wide range of different wavelengths reveals features that would otherwise remain invisible.

During the 1960s, scientists discovered a massive radio source (known as Sagittarius A*) at the center of the Milky Way, which was later revealed to be a Supermassive Black Holes (SMBH). Since then, they have learned that these SMBHs reside at the center of most massive galaxies. The presence of these black holes is also what allows the centers of these galaxies to have a higher than normal luminosity – aka. Active Galactic Nuclei (AGNs).

On October 19th, 2017, the Panoramic Survey Telescope and Rapid Response System-1 (Pan-STARRS-1) in Hawaii announced the first-ever detection of an interstellar asteroid, named 1I/2017 U1 (aka. ‘Oumuamua). Originally thought to be a comet, this interstellar visitor quickly became the focus of follow-up studies that sought to determine its origin, structure, composition, and rule out the possibility that it was an alien spacecraft!

Some truly interesting and ambitious missions have been proposed by NASA and other space agencies for the coming decades. Of these, perhaps the most ambitious include missions to explore the “Ocean Worlds” of the Solar System. Within these bodies, which include Jupiter’s moon Europa and Saturn’s moon Enceladus, scientists have theorized that life could exist in warm-water interior oceans.

When is a Brown Dwarf star not a star at all, but only a mere Gas Giant? And when is a Gas Giant not a planet, but a celestial object more akin to a Brown Dwarf? These questions have bugged astronomers for years, and they go to the heart of a new definition for the large celestial bodies that populate solar systems.

Research suggests that microbes may one day help astronauts on deep-space missions turn human waste into food.

On the evening of Jan. 31, 1958, the United States orbited its first satellite -- Explorer 1. The effort was part of the nation's participation in the International Geophysical Year (IGY), a peaceful scientific endeavor. It also marked America's first step in the Space Race of the Cold War.

When it comes to looking beyond our Solar System, astronomers are often forced to theorize about what they don’t know based on what they do. In short, they have to rely on what we have learned studying the Sun and the planets from our own Solar System in order to make educated guesses about how other star systems and their respective bodies formed and evolved.

The most massive planets possible are equivalent of nearly 3,200 Earths.

We are not used to considering dust as a valuable material – unless it comes from space. And more precisely, from the comet 67P/Churyumov-Gerasimenko. An analysis of its dust has provided valuable information about this celestial object, and, more generally, on the history of the Solar System.

Astronomers have been fascinated with globular clusters ever since they were first observed in 17th century. These spherical collections of stars are among the oldest known stellar systems in the Universe, dating back to the early Universe when galaxies were just beginning to grow and evolve. Such clusters orbit the centers of most galaxies, with over 150 known to belong to the Milky Way alone.

A small asteroid passed relatively close to Earth this month, having been discovered just six days earlier. This might sound scary, but it’s unusual that such an object would actually collide with the Earth.

A telescope can reveal the beauty of the universe, such as the Moon’s craters, Saturn’s rings, and the glowing gas of the Orion nebula. But a telescope isn’t just for sightseeing – it is also a scientific instrument.

In the 1970s, astronomers discovered that a particularly large black hole (Sagittarius A*) existed at the center of our galaxy. In time, they came to understand that similar Supermassive Black Holes (SMBHs) existed in the center of most massive galaxies. The presence of these black holes was also what differentiated galaxies that had particularly luminous cores – aka. Active Galactic Nuclei (AGN) – from those that didn’t.

NASA’s Juno spacecraft was a little more than one Earth diameter from Jupiter when it captured this mind-bending, color-enhanced view of the planet’s tumultuous atmosphere.