#preplanetary-nebula

#preplanetary-nebula

The new work was less notable for showing that we had found these bases in Ryugu than for solving a previous mystery: earlier studies had failed to detect them there, despite their presence in many other asteroid samples.

We found that life is more likely to survive an asteroid impact, so it's definitely still a real possibility that life on Earth could have come from Mars. Maybe we're Martians! The idea that life could have spread through the solar system or even the universe on rocks is known as the lithopanspermia hypothesis.

A bright star in a nearby galaxy has essentially vanished. Astronomers believe that it died and collapsed in on itself, transforming into the eerie cosmic phenomenon known as a black hole. "It used to be one of the brightest stars in the Andromeda galaxy," says Kishalay De, an astronomer with Columbia University and the Flatiron Institute. "Today, it is nowhere to be seen, even with the most sensitive telescopes."

Looking skyward fills us with wonder. Off-world, the Sun, planets, stars, and galaxies all await. Our Solar System encompasses our own cosmic backyard. Farther away, stars and star clusters abound within the Milky Way. Hundreds of billions of stars exist just within our home galaxy. Inside our Local Group, only Andromeda surpasses us in mass, size, and stars. More than 5 million light-years away, galaxies abound in groups and clusters.

This system is truly extraordinary. We're seeing the radio equivalent of a laser halfway across the universe. Fundamentally, masers and lasers are focused beams of light in the same frequency. In the realm of astrophysics, these can arise from clouds of dust being excited into a higher energy state from the light emitted by other sources, like stars and black holes.

The population of super-Earths and sub-Neptunes, and the origin of the radius valley that separates these two classes of planets, is best explained by cores that are made of an Earth-like composition without a substantial amount of accreted ice8,9,10,11. For sub-Neptunes, the hydrogen-rich envelope overlies the rocky core for billions of years, whereas for super-Earths, the envelope may be retained for about 100 Myr (refs. ).

The universe is exploding. Or parts of it are. The night sky may seem calm, even serene, but that masks events of a catastrophic and nearly unimaginable scale. Across the galaxy and even the cosmos itself, immense outbursts of energy occur that could easily vaporize our planet. Happily, space is vast, and the terrible distance between these events and us diminishes what we see to a faint glowusually.

Okay, first thing first: the universe is in fact expanding. We've known this for more than a century now, and it's the basis for modern cosmology. This idea is called the big bang modelwhich is an unfortunate name because it brings to mind a cosmos expanding like an explosion, with galaxies moving away from each other through space like shrapnel. But in fact space itself is expanding, and that's different.

One of the most exciting aspects is the rich chemistry we detect. We see dozens of different molecules, including some complex organic molecules that contain carbon, the same element that forms the basis of life on Earth. From ACES, we are learning more about how the ingredients for planets, and potentially life itself, can arise in the universe.