Space

Celebrating 20 years of exoplanet discovery

Artists impression of a gas giant exoplanet passing across the face of its star
Artists impression of a gas giant exoplanet passing across the face of its star
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Artists impression of a gas giant exoplanet passing across the face of its star
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Artists impression of a gas giant exoplanet passing across the face of its star
Artists impression of the Kepler space telescope in orbit
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Artists impression of the Kepler space telescope in orbit
Artists impression of Kepler-10c
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Artists impression of Kepler-10c
Artist's impressionof Beta Pictoris b
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Artist's impressionof Beta Pictoris b
Artists impression of the enormous ring system present around the exoplanet orbiting the young star J1407b
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Artists impression of the enormous ring system present around the exoplanet orbiting the young star J1407b
Artists impression of HD 189733b transiting in front of its parent star
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Artists impression of HD 189733b transiting in front of its parent star
Artists impression of 51 Pegasi b
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Artists impression of 51 Pegasi b
Artists impression of Earth on the left, with its larger "cousin" Kepler-425b pictured on the right
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Artists impression of Earth on the left, with its larger "cousin" Kepler-425b pictured on the right
Artist's impression of sunrise over CoRoT-7b
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Artist's impression of sunrise over CoRoT-7b
More than 1800 exoplanets have been discovered over the past two decades
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More than 1800 exoplanets have been discovered over the past two decades

This month marks the 20th anniversary of the first discovery of a planet orbiting a Sun-like star outside of our solar system – 51 Pegasi b. This event represented a watershed moment in astronomy, and since this point, over 1,800 exoplanets have been discovered, with over 1,000 spotted by NASA's Kepler space telescope.

The study of exoplanetshas revolutionized our understanding of the laws governing thegreater mechanisms at work throughout the cosmos. The observationshave allowed us to gain an appreciation of how unique our own solarsystem is, while granting us a glimpse at the incredibly variednature of our galaxy.

We understand that ourplanet exists at the ideal distance from the Sun for the evolution oflife, and that by searching for exoplanets that share similarcharacteristics with Earth, we can determine the habitability ofplanets orbiting distant stars.

Artists impression of the Kepler space telescope in orbit
Artists impression of the Kepler space telescope in orbit

The technologicaladvances that have taken place since the discovery of 51 Pegasi b onOctober 6 1995 have allowed us to gain ever more complexinsights regarding the nature of these remote worlds. Asthe methodology matures, we arelearning to characterize the atmospheres present around them in evergreater detail, and from these observations, infer the prevailing surface conditions.

To celebrate two decades of otherworldly discovery, we've created a list of someof the weirdest, wondrous, and significant exoplanets identified to date.

Kepler-10c

A planet so large itshouldn't even exist. Imaginatively dubbed a "mega-Earth"by astronomers at the Harvard-Smithsonian Center for Astrophysics,the planet weighs in around 17 times the mass of our home world, andis so massive that it defies contemporary theories on planetaryformation.

Artists impression of Kepler-10c
Artists impression of Kepler-10c

Beta Pictoris b

Beta Pictoris b was the first planet tohave the length of its day measured. A fullday on this massive planet lasts a mere eight Earth hours, as it spins at the ridiculous speed of 100,000 km/h (62,000 mph).

Artist's impressionof Beta Pictoris b
Artist's impressionof Beta Pictoris b

Exoplanet ring systemorbiting J1407b

This selection isn'tbased on the planet itself, but rather the impressive ring system ithosts. The exoplanet with a mass somewhere between 10 - 40 timesthat of Jupiter is believed to host a ring system around 200 timeslarger than that of Saturn. The vast rings were discovered thanks tothe pattern of unusual eclipses made as they passed in front of theexoplanet's young star J1407b.

Artists impression of the enormous ring system present around the exoplanet orbiting the young star J1407b
Artists impression of the enormous ring system present around the exoplanet orbiting the young star J1407b

HD 189733 b

This tidally lockedexoplanet is basically a realtor's nightmare. Described as a "hotJupiter", HD 189733 b sits only 4.65 million km (2.9 millionmiles) away from its parent star, giving it an average temperature of800ºC (1,472ºF) and winds closing on 6,000 miles per hour (9,656km/h). Oh, and also there's silicate snow showers, because space isfun.

Artists impression of HD 189733b transiting in front of its parent star
Artists impression of HD 189733b transiting in front of its parent star

51 Pegasi b

Another exoplanetcategorized as a "hot Jupiter", 51 Pegasi b has two claimsto fame. As previously noted, it was the first planet to bediscovered around a Sun-like star, but after further observation fromthe High Accuracy Radial velocity Planet Searcher (HARPS) instrumentmounted on the ESO's 3.6 meter telescope, it also became the firstexoplanet to be observed in the visible light spectrum.

Artists impression of 51 Pegasi b
Artists impression of 51 Pegasi b

Kepler-425b

Described by NASA as"Earth's bigger, older cousin", Kepler-425b represents themost habitable exoplanet discovered to date. The planet, which isaround 60 percent larger than Earth, orbits in its star's habitablezone, meaning that it is possible for liquid water to exist on itssurface. The planet also shares a star with characteristics similarto our Sun, has a yearly cycle of 385 days and hosts a atmosphere atleast as thick as Earth's.

Artists impression of Earth on the left, with its larger "cousin" Kepler-425b pictured on the right
Artists impression of Earth on the left, with its larger "cousin" Kepler-425b pictured on the right

Exoplanet PH3c

It's tough keeping time on PH3c. The unusual orbit ofthe exoplanet causes extreme variations in the length of its yearly cycle,making the exoplanet impossible to detect via conventional methods.The cause of PH3c's eccentric orbit appears to be down togravitational influence from nearby planets, resulting in adistortion in its orbital period of roughly 10.5 hours over thecourse of only 10 orbits.

More than 1800 exoplanets have been discovered over the past two decades
More than 1800 exoplanets have been discovered over the past two decades

COROT-7b

Discovered in 2009, COROT-7b has a similar density and silicate rock makeup to that of Earth. One side of the exoplanet always faces towards its Sun, and this side is thought to have a temperature of 4220°F. Scientists have theorized that this all adds up to a planet where instead of raining water, it rains rocks!

Artist's impression of sunrise over CoRoT-7b
Artist's impression of sunrise over CoRoT-7b

These are just a tinysample of the plethora of diverse exoplanets discovered during the past two decades. Wecan only imagine, with a new generation of planet huntingobservatories and techniques, what discoveries the next 20 years willbring.

Source: NASA

1 comment
2_OK
Interesting, having exoplanets! However, if there are aliens they might encript they way of comunication any way to prevent some "humans" creatures to figure it out. Fun for real!