Today we have some exciting news from out there in the solar system [checks notes] er, excuse me, I guess I mean “in there” in the solar system, since today’s news concerns from the planet closest to the sun. Yet, even though it is first, Mercury is shockingly unknown compared to the other planets of the solar system. This past Friday (October 1st 2021), the joint ESA/JAXA space mission BepiColombo (which launched back in 2018) finally made it to the innermost world. Since 2018, the transfer module has been slaloming around Earth and Venus in order to make it to Mercury. Indeed, the mission is named after the brilliant Italian astrophysicist who first proposed interplanetary gravity assist maneuvers as a mechanism for altering the velocity and trajectory of interplanetary spacecraft. BepiColombo took the picture at the top of this post, a view of part of Mercury’s northern hemisphere taken at a distance of about 2,420 kilometers (1,500 miles) from the world.

In 2025, the spacecraft will deploy two orbiters to truly comprehensively map Mercury and attempt to unlock the mysteries of the planet’s ancient face. Mercury’s surface seems to be made of a very dark lava which has been bombarded by meteorites for the last several billion years. Although Mercury is dinky in volume (smaller than some of the solar system’s moons) it is quite dense and presumably contains a metallic core suitable for a much larger planet. Interestingly (albeit unsurprisingly, for anyone who lives here) the densest planet in the solar system is Earth!

Not since the end of the Messenger mission has Mercury been the thrilling center of attention in astronomy. I can hardly wait for subsequent discoveries about the fast, hot, tiny planet. Some of the secrets of the making of the solar system have been locked away on the little world, waiting billions of years for the right orbiter to come along.

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