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Nearest Exoplanet to Earth

Currently, the nearest claimed exoplanet to Earth is alpha Centauri B b, and as its name suggests, it resides in the nearest star system to Earth (which is a binary). The distance to Earth is about 4.24 light years, and the planet orbits with a period of 3.2357 Earth days, very close in to the star alpha Centauri B (only 4% of the Earth-Sun distance). The lower limit on the planet's mass is about 1.14 Earth masses, and there is no radius estimate. See Dumusque et al. 2012, Nature. However, you should be aware that the planet's existence is probabilistic because of the statistical nature of extracting the planet's signal from that of the complex overall signal from the binary star system. Therefore, it is possible that the result could be a false alarm. For a spacecraft traveling at 20,000 miles per hour (which is achievable already), it would take about 142,000 years to get to the planet from Earth.

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Currently the second-nearest exoplanet to Earth found so far goes by the rather tedious name of eps Eridani b. It is located at about 10.44 light years from Earth, which means that it would take light about 10.44 years to travel from Earth to the planet. For a spacecraft traveling at 20,000 miles per hour, it would take about 350,000 years to get to the planet from Earth. The planet was discovered in 2000. Thus, eps Eridani b has held the record for being the nearest exoplanet to Earth for about 12 years.

This second-nearest exoplanet, eps Eridani b, has a mass (lower bound) of approximately 1.5 times the mass of Jupiter, and there is no radius (size) measurement. It is located at about 3.4 times the Earth-Sun distance from its host star, and has an orbital period of 2502 Earth days (references for these numbers can be found in the Extrasolar Planets Encylopedia eps Eridani entry). The host star has about 80% of the mass of our Sun, and is somewhat cooler than our Sun by about 1000 degrees (the surface temperature of eps Eridani is about 4800 degrees Celsius, or 8750 degrees Fahrenheit).

If you would like to be able to find out yourself what is the closest exoplanet found so far, here is how you do it. Go to the Extrasolar Planets Encylopedia and click on the button in the header of the table that says “All fields” and then click on the column called Distance. When you click on it, the data in the table should be sorted in order of numerical value in that column (i.e., the distance between Earth and the planets). An arrow just to the right of the word Distance tells you whether the numerical order is ascending or descending (the arrow will point upwards for an ascending order). If you click the column header again, the numerical ordering will flip from ascending to descending or vice versa. To find the closest exoplanet to Earth you want the distance measurements to be ascending, with the smallest values appearing first. However, the rows that appear first may have no entries in the Distance column and if so, these correspond to exoplanets for which the distance from Earth has not been measured. Scroll down until you see the first non-blank entry in the Distance column. That is the nearest exoplanet and the number in the cell is the distance to the nearest exoplanet in units called parsecs. You can convert these to any other units by typing an appropriate statement in a Google search box. The conversion factor from parsecs to light years is such that you multiply parsecs by 3.26 to get light years.

Revision history: This article was last updated on: 20 October 2012.

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