Top 10 Exoplanets: Weird Worlds in a Galaxy Not So Far Away [Slide Show]
A look at some of our extreme planetary neighbors right here in the Milky Way Galaxy
![Top 10 Exoplanets: Weird Worlds in a Galaxy Not So Far Away [Slide Show]](https://static.scientificamerican.com/sciam/cache/file/9880B98A-3B83-4D8E-9133CB6A5F7EEAB3.jpg?w=590&h=393)
Top 10 Exoplanets: Weird Worlds in a Galaxy Not So Far Away [Slide Show]
- BONUS: FIRST PROTOPLANET?: Though no exoplanets have been confirmed around a star called UX Tauri A, scientists have spotted a huge gap in its protoplanetary disk indicating that a planet may be coalescing. These swirling disks of gas and dust (leftover material from star formation) form around a star's equator and then extend outward into space... NASA/JPL-Caltech
- 1. PRIMORDIAL PLANET: Exoplanet PSR B1620-26 b is believed to have formed an incredible 13 billion years ago, less than a billion years after the big bang. Aptly nicknamed Methuselah, this probable gas giant resides in an ancient type of galaxy known as a globular cluster, where it orbits two stellar hosts, a white dwarf star and a pulsar, both remnants of larger stars... NASA/G Bacon
- 2. EARTH TIMES THREE: The exoplanet MOA-192 b, which orbits a purplish star in this artist's impression, is the smallest discovered so far, measuring about 3.3 Earths in mass. It revolves about a dim star that is about one twentieth the mass of our sun, making this the planet with the teensiest host star, to boot... NASA's Exoplanet Exploration Program
- 3. IT'S A SMALL(ER) WORLD: Besides being the first exoplanet ever directly observed from Earth as it transited in front of its host star, exoplanet HD 209458 b (aka Osiris) is also shrinking. Its proximity to the inferno of its host star superheats the planet to an estimated 18,000 degrees Fahrenheit (10,000 degrees Celsius), which researchers believe is causing it to sweat off about 10,000 tons (9,000 metric tons) of atmospheric hydrogen every second, forming a cometlike tail... ESA/Hubble
- 4. EXOHOTTIE: HD 149026 b ranks as one of the hottest known exoplanets, with a lead-boiling surface temperature of around 3,700 degrees Fahrenheit (2,000 degrees Celsius). Tricky measurements of light reflecting from its surface suggest that this world may be pitch-black in color, perhaps because of a strangely high concentration of heavy, metallic elements in its atmosphere... NASA/JPL-Caltech; N2K Consortium
- 6. FREAKISHLY FROZEN WORLD: Scientists think Gliese 436 b (aka GJ 436 b), a Neptune-size exoplanet, is too heavy to be all gas but not heavy enough to be entirely rock. They surmise that in addition to gas and rock, it also contains a kind of pressurized, high-temperature ice that only exists on Earth in laboratories, where it goes by names like "ice VII" and "ice X." The high pressures deep inside the planet may stabilize this alternate solid state of water, similar to the way intense pressures in Earth's crust can squeeze carbon atoms into crystalline diamond... Lynette Cook, courtesy of Geoff Marcy
- 9. TYPICAL STAR; EXTRAORDINARY PLANET: The first exoplanet spotted around a typical or "main sequence" star similar to our sun, gaseous 51 Pegasi b completes an orbit around its host star every four days. Many exoplanets found after this one are very similar "hot Jupiters," named for their size and proximity to their star... Debivort
- 10. FIRST EXOWORLD: The first solid evidence for an exoplanet (extrasolar planet) came in 1992 when scientists calculated that two bodies must be orbiting the pulsar PSR 1257. Pulsars are rapidly spinning neutron stars (the superdense remnants of massive stars that have exploded as supernovae), which emit radio waves in pulses... NASA/JPL-Caltech
