Latest Articles
The Cosmic Microwave Background: Light from the Edge of the Observable Universe
Look out into space far enough, and you will hit a wall. Not a physical barrier, but an epoch, a moment in the universe‘s history when it was so hot and dense that it was opaque. But we can detect the glow of that wall itself. The cosmic microwave background (CMB) is the oldest light…
Gravitational Waves: How Ripples in Spacetime Changed Astronomy
On September 14, 2015, at 5:51 a.m. Eastern time, two black holes collided 1.3 billion light-years away. Seven milliseconds later, a signal arrived at the LIGO detector in Livingston, Louisiana, and then at the Hanford, Washington detector: a pattern of stretching and squeezing in spacetime so tiny that it displaced the detectors’ mirrors by a…
Super-Earths in the Habitable Zone: Why Kepler-22b Is the Benchmark for a New Class of Worlds
The first Earth-like world we found wasn’t Earth-like at all. It was called a super-Earth, though that classification would later prove contested, and it might not even be solid. Kepler-22b, discovered in 2011, was the first confirmed planet in the habitable zone of a Sun-like star. It has a radius 2.4 times that of Earth,…
Kepler-22b Habitability: Why the Unknown Mass Is the Central Question
Of the thousands of exoplanets confirmed since the first detection in 1992, only a handful sit in the right place, around the right star, at the right distance to make the question worth asking seriously: could this world support life? Kepler-22b habitability is the question this article addresses: what do we actually know, and what…
Kepler-22b vs Earth: A Side-by-Side Comparison of Two Worlds in the Habitable Zone
The Kepler-22b vs Earth comparison starts with a striking coincidence: both planets receive nearly identical amounts of starlight. Kepler-22b gets almost the same amount of starlight as Earth. It has a similar year and orbits a near-twin of our Sun. So why aren’t scientists calling it Earth 2.0? A Kepler-22b vs Earth comparison starts with…
The Big Crunch: What Happens If Gravity Wins the Universe
Imagine the history of the universe (the birth of galaxies, stars, planets, life) played in reverse, faster and faster, until everything merges into a single, searing point. This is the Big Crunch. The universe is currently expanding. Every galaxy beyond our Local Group is moving away from every other, carried apart by the growth of…
