Last week we covered multiple star systems, but what if we added thousands or even millions of stars to the mix? A star cluster. There are different kinds of clusters, though. Open clusters contain hundreds or thousands of stars held together by gravity. They’re young, and evaporate over time, their stars let loose to roam space freely. Globular clusters, on the other hand, are larger, have hundreds of thousands of stars, and are more spherical. They’re very old, a significant fraction of the age of the Universe itself, and that means their stars have less heavy elements in them, are redder, and probably don’t have planets (though we’re not really sure).
Artificial selection is one example, eyes another, of the well-documented and inescapable process of evolution--change in a population of species over time--by natural selection. These are some of the things that molecules do.
The majority of the universe is made up of a currently mysterious entity that pervades space: dark energy. We don’t know exactly what it is, but we do know that dark energy accelerates the expansion of space. We think this means the Universe will expand forever, even as our view of it shrinks while space expands faster all the time.
Twenty years after its launch, we bid farewell to the Cassini spacecraft as it plunges into Saturn’s atmosphere in a planned death spiral. Productive right to the end, Cassini has rewritten the textbook on not only Saturn and its moons, but our whole solar system as well.
The universe is a dangerous place, and we explore the deadliest spots in the cosmos. Between earth and the edge of the universe, there are a million ways to die, and our crash test dummy is on a mission to reveal the worst.