With over 7 billion people on the planet, for many of us, the Earth is beginning to feel a little…crowded. The diameter of the Earth is some 7,900 miles (a little over 12,700 km). With that much space, it seems that each individual should have enough to be content. However, once you take into consideration all the acres needed to grow food and play football, things start to get a little congested.
But the next time you feel a bit claustrophobic, just be glad that you don’t call Kepler-37b your home.
About 210 light-years from Earth, there is a small and unassuming star known as Kepler-37. This star has a radius that is just ¾ of the sun. And orbiting this little star is a little planetary system (and we mean little). The Earth orbits the sun at an average distance of 96 million miles (150 million km). Yet, all of the planets found revolving around Kepler-37 (there are three, so far) have orbits that are less than 35 million miles from the searing solar surface (56 million km).
Kepler mission scientists analyzing the star recently found a staggeringly small planet, Kepler-37b, which is the smallest planet ever discovered. This tiny object has a diameter of a mere 2,400 miles (3,800 km). Remember, the Earth is 7,900 miles in diameter (12,800 km). Imagine trying to cram 7 billion humans onto a planet that is only about one-third the size of the Earth (it would be unpleasant, to say the least).
Fortunately, we won’t be relocating anytime soon.
Although the tiny planet is almost certainly rocky in composition, since it is so close to its star (orbiting at a mere 9 million miles, or 15 million km, from Kepler-37), astronomers believe that Kepler-37b does not have an atmosphere and, as a result, cannot support life as we know it (no atmosphere, no air-- no air, no breathing-- no breathing, no us…it’s simple really).
Kepler-37b orbits every 13 days at less than one-third Mercury's distance from the sun, which is a little too close for comfort. Such a small orbital distance means that the planet is hot. Very hot. The estimated surface temperature of this hellish planet is more than 800 degrees Fahrenheit (700 degrees Kelvin). This would be hot enough to melt the zinc in a penny…poor old Abe.
The first exoplanets found orbiting a star were giants. This seems obvious, as larger planets are easier to detect. However, technology has developed quite a bit since the first planet hunters started looking to the skies. As a result, smaller and smaller planets are continually being discovered. To discover this little world, the research team used data from NASA's Kepler space telescope, which simultaneously and continuously measures the brightness of more than 150,000 stars every 30 minutes.
Jack Lissauer, a planetary scientist at NASA's Ames Research Center, notes: "The fact we've discovered tiny Kepler-37b suggests such little planets are common, and more planetary wonders await as we continue to gather and analyze additional data."
Until then, we wait with bated breath...
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