White dwarf stars, the remnant cores of low-mass stars that have exhausted all their nuclear fuel, are among the most dense objects in the sky. Their mass is comparable to that of the sun, while their volume is comparable to that of Earth. Very roughly, this means the average density of matter in a …
Continue reading "Of White Dwarfs, "Zombie" Stars and Supernovae Explosions"
Asteroid, we've long been told, started tiny in our protoplanetary disk and only very gradually became more massive through a process of accretion. They collected dust from the gas cloud that surrounded our new star, and then grew larger through collisions with other growing asteroids. But in recent years, a new school of thought …
Continue reading "Primordial Asteroids, And The Stories They Are Telling"
Sometimes tectonic shifts in scientific disciplines occur because of discoveries and advances in the field. But sometimes they occur for reasons entirely outside the field itself. Such appears to be case with origins-of-life studies. Nobel laureate Jack Szostak was recently in Tokyo to participate in a workshop at the Earth-Life Science Institute (ELSI) at the …
One of the great successes of the Curiosity mission to Mars is that the rover landed at what turned out to be a goldmine of a location. The mission has once and for all determined that the planet was habitable at least during its early days, that it contains the organic building blocks of life, …
Continue reading "Where Should We Look for Ancient Biosignatures on Mars in 2020?"
It wasn't that long ago that Enceladus, one of 53 moons of Saturn, was viewed as a kind of ho-hum object of no great importance. It was clearly frozen and situated in a magnetic field maelstrom caused by the giant planet nearby and those saturnine rings. That view was significantly modified in 2005 when scientists …
Seldom has the planned end of a NASA mission brought so much expectation and scientific high drama. The Cassini mission to Saturn has already been a huge success, sending back iconic images and breakthrough science of the planet and its system. Included in the haul have been the discovery of plumes of water vapor spurting …
Continue reading "What Scientists Expect to Learn From Cassini’s Upcoming Plunge Into Saturn"
In the late stages of the formation of Earth, the planet was a brutally hot, rough place. But perhaps not precisely in the way you might imagine. Most renderings of that time show red-hot lava flowing around craggy rocks, with meteorites falling and volcanoes erupting. But according to those who study the time, the reality …
Let your mind wander for a moment and let it land on the most exciting and meaningful NASA mission that you can imagine. An undertaking, perhaps, that would send astronauts into deep space, that would require enormous technological innovation, and that would have ever-lasting science returns. Many will no doubt think of Mars and the …
The Many Worlds site has been down for almost two weeks following the crash of the server used to publish it. We never expected it would take quite this long to return to service, but now we are back with a column today and another one for early next week. Earth is most fortunate to …
For most of us, asteroids exist primarily as a threat. An asteroid that landed around the Yucatan peninsula, after all, is generally considered to have set into motion the changes that resulted in the elimination of the dinosaurs. Other large in-coming asteroids laid waste to swaths of Siberia in 1908, dug the world's largest crater …
Many Worlds 