Before there were planets in our solar system, there was a star that would become our sun. Before there was a sun, there were older stars and exoplanets throughout the galaxies. Before there were galaxies with stars and exoplanets, there were galaxies with stars and no planets. Before there were galaxies without planets, there were …
Proxima b Is Surely Not "Earth-like." But It's A Research Magnet And Just May Be Habitable.
It is often discussed within the community of exoplanet scientists that a danger lies in the description of intriguing exoplanets as "Earth-like." Nothing discovered so far warrants the designation, which is pretty nebulous anyway. Size and the planet's distance from a host star are usually what earn it the title "Earth-like," with its inescapable expectation …
The Case Strengthens For "Planet 9"
The race is on to find the giant planet that several teams of astronomers are convinced orbits far out beyond Pluto, but is nonetheless still part of our solar system. Proving the existence of what has become known as Planet X, or Planet 9, would be a discovery for the textbooks and would inevitably change …
Found: Our Nearest Exoplanet Neighbor
No exoplanet can possibly be closer to us than the one just detected around our nearest stellar neighbor, Proxima Centauri. The long-sought and long-imagined planet is larger than Earth, but small enough to be rocky as opposed to a gas or ice giant. Making things even more exciting, the planet was detected inside the habitable …
Earth: A Prematurely Inhabited Planet?
The study of the formation and logic of the universe (cosmology) and the study of exoplanets and their conduciveness to life do not seem to intersect much. Scientists in one field focus on the deep physics of the cosmos while the others search for the billions upon billions of planets out there and seek to …
The Ever More Puzzling, And Intriguing, "Tabby's Star."
Substantial, sun-like stars are not supposed to dim. They start with gravity and pressure induced nuclear reactions, and then they burn brighter and brighter until they either explode (go supernova) or burn all their fuel and become small, enormously dense, and not very bright "white dwarfs." Of course, the transit technique of searching for exoplanets …
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Coming to Terms With Biosignatures
The search for life beyond our solar system has focused largely on the detection of an ever-increasing number of exoplanets, determinations of whether the planets are in a habitable zone, and what the atmospheres of those planets might look like. It is a sign of how far the field has progressed that scientists are now …
Rocky, Close and Potentially Habitable Planets Around a Dwarf Star
Forty light-years away is no small distance. But an announcement of the discovery of two planets at that separation that have been determined to be rocky and Earth-sized adds a significant new twist to the ever-growing collection of relatively close-by exoplanets that just might be habitable. The two planets in the TRAPPIST-1 system orbit what …
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Rethinking The Snow Line
In every planet-forming disk there's a point where the heat from a host star needed to keep H2O molecules as vapor peters out, and the H2O be becomes a solid crystal. This is the snow line, and it looms large in most theories of planet formation. Most broadly, planets formed inside the snow line will …
Three Star Ballet, With Exoplanet
It hardly seems possible, but researchers have detected a planet in apparently stable orbit within a three star system -- a configuration now known as a trinary. The ubiquity of binary stars has been understood for some time, and the presence of exoplanets orbiting around and within them is no longer a surprise. But this …
Many Worlds 