With no stars to illuminate them, rogues are mostly great big unknowns to scientists.
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| © OGLE With no stars to illuminate them, rogues are mostly great big unknowns to scientists. |
By David Grossman, Popular Mechanics
Rogue planets wander through space without orbiting a star, and now
scientists have found two more of these free-floating worlds.
For centuries, the very existence of rogue planets was hypothetical.
Because they're not close to a star that lights them up, they're
tremendously difficult to spot. Then a technique known as gravitational
microlensing came around.
Using gravitational microlensing,
scientists find planets by noting when a rogue planet interrupts a
star's light from our point of view. The planet suddenly acts as a lens
for the star's light, curving it as it would be seen from Earth. The
bigger the planet, the bigger the interruption.
It's not the most efficient system. Some astronomers (like Neil DeGrasse Tyson) estimate there are billions of rogue planets within the Milky Way. But while humanity has proven great at finding exoplanets
attached to stars, scientists have only identified a dozen or so
rogues. That's what makes adding two more to the pile such a big deal.
The
planets are officially called OGLE-2017-BLG-0560 and
OGLE-2012-BLG-1323, respectively, and there's a lot we don't know about
them. Their names stem from how they were discovered, at the Optical Gravitational Lensing Experiment
at the Las Campanas Observatory in Chile. The first one could be
anywhere from the size of Jupiter to the size of 20 Jupiters, while the
latter is between the size of Earth and Neptune. Nothing is known about
how far they are from the solar system.
Scientists are hoping that the Transiting Exoplanet Survey Satellite,
launched April 16, will give exoplanet and rogue planet hunters a new
advantage in learning more about the mysterious bodies that apparently
surround the solar system.
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