In the United States, the day after Thanksgiving is commonly referred to as Black Friday — so called because the money shoppers spend tips retailers from “the red” into “the black,” according to Oxford. On this day, millions of crazed shoppers pack tightly into stores, trying to amass bargains. On Nov. 24, 2014, NASA decided to give the day another meaning: Black Hole Friday. On this day each year, NASA features gorgeous illustrations and details about one of the most cosmically cool space discoveries in the known universe. As a follow-up to Black Hole Friday, these facts about black holes are sure to take your mind off the holiday madness.

Black Holes May Connect to Other Universes

Black holes are celestial objects with gravity so immense no object can escape. It’s been said that to fall into a black hole is to never return. But according to an announcement in 2016 from the famous astrophysicist Stephen Hawking, falling into a black hole may not be all that bad. In a research paper he published with other colleagues, Hawking asserted that a black hole could be a tunnel between two universes, said Independent.

The Milky Way May Have Thousands of Them

In 1974, scientists discovered a huge, highly energetic structure at the center of the Milky Way that was emitting radio waves. It was a black hole. They named it Sagittarius A* (pronounced “Sagittarius A-star”), according to the Cornell University Library. For years, people thought Sagittarius A* was the only black hole at the center of our galaxy. But in May 2018, scientists analyzing data from NASA’s Chandra X-ray Observatory — a satellite designed to detect X-ray emissions from exploded stars, clusters of galaxies and black holes — announced that they found evidence for the existence of thousands of black holes at the center of the Milky Way. More work is needed to confirm this, but one thing is for sure: Sagittarius A* is not alone.

There Are Four Categories

Not all black holes are created equal. Scientists tend to classify black holes into four categories: micro, stellar, intermediate and supermassive, said Earth Eclipse. Although they vary in size, they are all very dense. Miniature black holes, which are still theoretical, may be as small as an atom but have the mass of a mountain. Stellar black holes, the most common in the universe, have the mass of 10 to 20 of our suns. Intermediate black holes are about the size of Earth and have the mass equivalent to something between 100 and a million suns. Supermassive black holes, which likely exist at the center of most galaxies, are “millions, if not billions, of times as massive as the Sun,” said NASA.

Black Holes Have a Big Appetite

One of the most fascinating space discoveries about black holes is that they are voracious eaters. Their incredible mass and intense gravity draw nearby cosmic gases and structures toward them, sparing nothing. In September 2018, scientists reported that they had calculated the speed at which one black hole, located billions of miles from Earth, was eating a glob of material about the size of our planet; it came out to one-third the speed of light, according to Science Trends.

An Image Capture May Be Available Soon

Thanks to a variety of astronomical satellites and instruments launched into space, scientists have created wonderful images of our solar system’s planets, distant stars, galaxies and other objects from this home we call our universe. But one character is missing: Sagittarius A*, the largest black hole at the center of the Milky Way galaxy. Enter the Event Horizon Telescope, a planetary array of multiple earthbound telescopes and instruments working together to directly image Sagittarius A* to gather more facts about black holes. The telescope is named after a feature on a black hole known as the event horizon, a boundary around the edge of a black hole beyond which no light or other radiation can escape. The team hopes to have the first image soon.