What was 51 Pegasi b, and why was its discovery significant?

The first planet found outside our solar system of any kind, discovered in 1991 around a pulsar The first confirmed exoplanet around a Sun-like star (1995), a gas giant with about half Jupiter's mass orbiting its star every 4.2 days The first Earth-sized exoplanet found in the habitable zone, discovered by the Kepler telescope The nearest exoplanet to Earth, orbiting the nearest star Proxima Centauri

What did the Kepler Space Telescope do, and how many exoplanets did it discover?

Kepler observed the solar system's planets with unprecedented resolution, finding new moons Kepler (2009-2018) stared at 150,000 stars simultaneously using the transit method and confirmed over 2,600 exoplanets Kepler discovered 10 exoplanets total, establishing the first census of planets around nearby stars Kepler measured the distances to millions of stars precisely, improving the cosmic distance scale

How many confirmed exoplanets were known as of 2024?

About 100 confirmed exoplanets — planet discovery remains rare and difficult Exactly 1,000 confirmed exoplanets — a milestone reached in 2014 Over 5,500 confirmed exoplanets, with thousands more candidates awaiting confirmation Over 1 million exoplanets — essentially every star studied has been found to have planets

What is a hot Jupiter?

A rocky planet the size of Jupiter found in the habitable zone of a red dwarf star A gas giant exoplanet orbiting very close to its star, with orbital periods of just days and surface temperatures of thousands of degrees Jupiter itself, which was once classified as a hot planet before it migrated outward A type of brown dwarf that orbits another star rather than existing as a free-floating object

What is a super-Earth, and why is it interesting?

A planet exactly 10 times the mass of Earth — the mass required to be labeled super A planet with 1.5-2 times Earth's radius, larger than Earth but smaller than Neptune — a type not found in our Solar System but extremely common elsewhere Earth itself, which is the largest rocky planet in the Milky Way A gas giant that has been stripped of its atmosphere, leaving only a dense rocky core

What are mini-Neptunes, and how common are they?

Small versions of Neptune that formed in our Solar System's asteroid belt Planets slightly smaller than Neptune with thick gas envelopes, 2-4 times Earth's radius — the most common type of planet discovered by Kepler Neptune-mass planets orbiting other stars at Neptune's distance from their star Planets that are actually moons of gas giants, discovered by the Kepler mission

What is a rogue planet?

A planet in an unusual, highly eccentric orbit around its star — not a circular orbit A planet not orbiting any star, traveling through interstellar space freely — possibly ejected from a planetary system during gravitational interactions A planet discovered by amateur astronomers without institutional support — a rogue discovery A planet that is gradually spiraling into its star due to tidal interactions

What does it mean that the Milky Way likely has more planets than stars?

Only the most massive stars have planets — smaller stars are typically planet-free Statistical analysis of exoplanet surveys suggests most stars have at least one planet, meaning the galaxy contains hundreds of billions of planets — more than its ~200-400 billion stars Planets are rare — only 1 in 1,000 stars has a planetary system like our Solar System Every star has exactly one planet — this has been confirmed by statistical studies

What is the TESS mission and how does it differ from Kepler?

TESS uses the radial velocity method while Kepler used the transit method TESS (2018-present) surveys the entire sky in two-year sectors, focusing on nearby bright stars to find planets suitable for follow-up atmospheric study TESS is a ground-based telescope array that replaced the Kepler satellite after its failure TESS directly images exoplanets by blocking their host star's light with a coronagraph

Which Nobel Prize was awarded for the discovery of exoplanets, and to whom?

The 2009 Nobel Prize in Physics, awarded to William Borucki for designing the Kepler telescope The 2019 Nobel Prize in Physics was shared by Michel Mayor and Didier Queloz for discovering 51 Pegasi b — the first exoplanet around a Sun-like star No Nobel Prize has been awarded for exoplanet discoveries — the committee considers it applied astronomy The 2015 Nobel Prize in Physics, awarded to Sara Seager for atmospheric characterization of exoplanets