Categories: Guide to SpaceMercury

What Are These Hollows on Mercury?

Emily Lakdawalla from the planetary society describes one of the mysteries that’s currently fascinating her. There are strange structures on Mercury which have been called “hollows”. What might they be?

“My name is Emily Lakdawalla – I’m the senior editor and planetary evangelist for the Planetary Society.”

What are the hollows on Mercury?

“Well, the Messenger mission has been mapping and orbiting Mercury and they’ve discovered these new kinds of features that nobody had ever seen before that they were calling hollows – they’re these pits in the ground, but they’re not impact craters. They look like somewhere where something has evaporated. They look like Swiss cheese – like that terrain at the south pole of Mars where the carbon dioxide cap is evaporating. They look kind of the same, except that this is mercury – there’s no carbon dioxide or water ice. It’s all gotta be solid rock.”

“So what exactly is evaporating to create these holes and how it’s disappearing from the ground is still a complete mystery. And the Messenger missions – they’re following up on the high-resolution imaging, but they still don’t have good info for what those hollows are.”

Are they similar to the caves on the Moon and Mars?

“The caves that have been found on the moon and Mars are likely skylights into lava tubes. There’s vulcanism all over the solar system – that’s how most of the surfaces of most of the surfaces of most of the planets were built – with lava spewing out. And wherever you have lava, you’ve got often a solid surface on the top and then liquid lava running underneath the surface. Eventually that drains and you get a hollow tube, and then maybe an earthquake happens or something opens a skylight down into the tube. So we’ve found cave skylights on both the moon and Mars, and of course on Earth.
I don’t know that we’ve found any of these on Mercury – I don’t think we have.”

Fraser Cain

Fraser Cain is the publisher of Universe Today. He's also the co-host of Astronomy Cast with Dr. Pamela Gay. Here's a link to my Mastodon account.

Recent Posts

SpaceX Reveals the Beefed-Up Dragon That Will De-Orbit the ISS

The International Space Station (ISS) has been continuously orbiting Earth for more than 25 years…

3 hours ago

Gaia Hit by a Micrometeoroid AND Caught in a Solar Storm

For over ten years, the ESA's Gaia Observatory has monitored the proper motion, luminosity, temperature,…

1 day ago

Lunar Infrastructure Could Be Protected By Autonomously Building A Rock Wall

Lunar exploration equipment at any future lunar base is in danger from debris blasted toward…

2 days ago

Why is Jupiter’s Great Red Spot Shrinking? It’s Starving.

The largest storm in the Solar System is shrinking and planetary scientists think they have…

2 days ago

ESA is Building a Mission to Visit Asteroid Apophis, Joining it for its 2029 Earth Flyby

According to the ESA's Near-Earth Objects Coordination Center (NEOCC), 35,264 known asteroids regularly cross the…

2 days ago

The Most Dangerous Part of a Space Mission is Fire

Astronauts face multiple risks during space flight, such as microgravity and radiation exposure. Microgravity can…

2 days ago