Why Didn’t the Big Bang Collapse in a Giant Black Hole?

This is an artist’s impression of a black hole drifting through our Milky Way galaxy. The black hole is the crushed remnant of a massive star that exploded as a supernova. The surviving core is several times the mass of our Sun. The black hole traps light because of its intense gravitational field. The black hole distorts the space around it, which warps images of background stars lined up almost directly behind it. This gravitational "lensing" effect offers the only telltale evidence for the existence of lone black holes wandering our galaxy, of which there may be a population of 100 million. The Hubble Space Telescope goes hunting for these black holes by looking for distortion in starlight as the black holes drift in front of background stars. Credit: ESA

Despite the enormous densities, the early universe didn’t collapse into a black hole because, simply put, there was nothing to collapse into.

Continue reading “Why Didn’t the Big Bang Collapse in a Giant Black Hole?”

A Brief History of the Discovery of Cosmic Voids

An artist's impression of the cosmic web, the filamentary structure that fills the entire Universe. Credit: M. Weiss/CfA

At first the sum total of large, orderly structure in the Universe appeared to arrive in two categories. There were the clusters of galaxies – an unoriginal but descriptive name – each a dense ball with anywhere from a few dozen to a few hundred galaxies, all bound together by their mutual gravitational embrace. And then there were the field galaxies, lonely wanderers set apart and adrift from the clusters, not bound to anyone but themselves. That was it: the clusters of galaxies, the field galaxies, and the megaparsecs of emptiness that enveloped them all.

Continue reading “A Brief History of the Discovery of Cosmic Voids”

Astronomers Prepare for the Next Thousand Years of Hazardous Asteroid Impacts

This diagram shows the orbits of 2,200 potentially hazardous objects as calculated by JPL’s Center for Near Earth Object Studies (CNEOS). Highlighted is the orbit of the double asteroid Didymos, the target of NASA’s Double Asteroid Redirect Test (DART) mission. Credit: NASA/JPL-Caltech

It is as inevitable as the rising of the Sun and the turning of the tides. Someday another large rock from space will crash into the Earth. It has happened for billions of years in the past and will continue to happen for billions of years into the future. So far humanity has been lucky, as we have not had to face such a catastrophic threat. But if we are to survive on this planet for the long term, we will have to come to terms with the reality of hazardous asteroids and prepare ourselves.

Continue reading “Astronomers Prepare for the Next Thousand Years of Hazardous Asteroid Impacts”

Astronomers Find a “Red Nova”: A Main-Sequence Star Just Eating its Planet

Artist's impression of a Jupiter-sized exoplanet orbiting an M-dwarf star

Back in 2020 astronomers observed a Red Nova, which while enormously powerful, is on the low side of energetic events in the universe. Now an astronomer has studied the event in close detail and has come to the conclusion that we have just witnessed a star destroying its own planet.

Continue reading “Astronomers Find a “Red Nova”: A Main-Sequence Star Just Eating its Planet”

What Cassini’s “Grand Finale” Taught Us About Saturn’s Interior

Six years ago the Cassini spacecraft, which had spent nearly two decades in orbit around Saturn, finished its mission with a grand finale, plunging itself into the depths of Saturn’s atmosphere. Those last few orbits and the final plunge revealed a wealth of information about Saturn’s interior. A team of astronomers have collected all of the available data and are now painting a portrait of the interior of the solar system’s second largest planet.

Continue reading “What Cassini’s “Grand Finale” Taught Us About Saturn’s Interior”

Black Holes Might be Defects in Spacetime

Artist view of a binary black hole system. Credit: LIGO/Caltech/MIT/Sonoma State (Aurore Simonnet)

A team of theoretical physicists have discovered a strange structure in space-time that to an outside observer would look exactly like a black hole, but upon closer inspection would be anything but: they would be defects in the very fabric of the universe.

Continue reading “Black Holes Might be Defects in Spacetime”

This Star Might be Orbiting a Strange “Boson Star”

Illustration of a merger of two boson stars. Credit: Nicolás Sanchis-Gual and Rocío García Souto

A team of astronomers has claimed that observations of a sun-like star orbiting a small black hole might actually be the indication of something far more exotic – the existence of a boson star, a star composed entirely of dark matter.

Continue reading “This Star Might be Orbiting a Strange “Boson Star””