Framed by an infinite backdrop of dark, lifeless space, a robotic arm on the International Space Station in 2015 mounted a box of exposed microbes on a handrail 250 miles above Earth. The hearty bacteria had no protection from an onslaught of cosmic ultraviolet, gamma, and x-rays. Back on Earth, scientists wondered whether the germs might survive these conditions for up to three years, the length of the experiment, and if they did, what the results might tell the researchers about the ability of life to travel between planets. Continue reading Scientists Discover Exposed Bacteria Can Survive in Space for Years
Last month, the massive, hot ball of glowing hydrogen and helium at the center of our solar system—otherwise known as our sun—released its largest solar flare since October 2017. Although it’s too early to know for certain, NASA says in a statement that this new activity might indicate that the sun is “waking up” from its cyclical slumber. Continue reading The Sun Produced Its Biggest Solar Flare Since 2017
The pair of stars in a system called HR 6819 is so close to us that on a clear night in the Southern Hemisphere, a person might be able to spot them without a telescope. What that stargazer wouldn’t see, though, is the black hole hiding right there in the constellation Telescopium. At just 1,000 light-years away, it is the closest black hole to Earth ever discovered, and it could help scientists find the rest of the Milky Way’s missing black holes. Continue reading Astronomers Discover the Closest Known Black Hole
At the center of the Milky Way galaxy, nearly 26,000 light-years away, a cluster of stars circles close to the supermassive black hole known as Sagittarius A*. As these few dozen stars, called S-stars, approach the black hole—which is about four million times more massive than the sun—its immense gravitational force whips them around faster than 16 million miles per hour. In fact, the gravitational pull of Sagittarius A* is so intense that it warps the light from these stars when they stray too close, stretching the wavelengths toward the red part of the electromagnetic spectrum. Continue reading A Star Orbiting in the Extreme Gravity of a Black Hole Validates General Relativity
At the center of a galaxy called Messier 87, about 55 million light-years away, about which all of the matter of the galaxy orbits, there lies a monster: a supermassive black hole. With about 6.5 billion times the mass of the sun, the black hole at the center of M87 is so dense that its escape velocity, or the velocity needed to escape the object’s gravity, is more than the speed of light. Accordingly, not even photons of light can escape once they wander too close.
The early universe was filled with strange and mysterious objects. Shortly after the Big Bang, large clouds of material may have formed black holes directly, without first coalescing into stars as we see today. Pseudo-galaxies lit up a sea of neutral hydrogen to make the universe transparent, releasing photons where before there was nothing but darkness. And short-lived stars made of nothing but hydrogen and helium may have flashed in and out of existence like sparks in the night. Continue reading Four Types of Stars That Will Not Exist for Billions or Even Trillions of Years
The most distant planetary exploration in history required a significant amount of careful planning and preparation, as well as a little bit of luck.