Thanks to satellite imagery, we now know that both Mars and the moon also have lava tubes and skylights. These caves and holes likely formed the same way they do on Earth.
As a channel of molten lava flows, its top layer, exposed to air, cools and forms a crust. Below, the hotter lava continues to course until it empties out, leaving behind a tube-like cave. Skylights form when parts of the lava tube ceiling collapse. Sometimes these ceilings crumble and completely block access to the cave. Other times, they fall away clean, leaving pits with dangerous, potentially unstable overhangs. But once in a while, the rocks fall in such a way to give unfettered access to a lava-carved tunnel.
June 14th, 2013
In Hawaii, as on Mars, Lava Tubes Hide Secrets Beneath the Surface Discover
August 18th, 2011
Spectacular sand pit found on Mars! Discover
Check. This. Out: a perfectly-formed collapse pit on Mars that leads to an underground cavern! This was taken by the Mars Reconnaissance Orbiter in July 2011. See the hole in the bottom? You can tell from the lighting that this is an underground opening to a cavern — a skylight. Quite a few of these have been found on Mars, actually. We see them on Earth and even on the Moon. Given the angle of the shadows, the vertical distance from the bottom of the pit to the floor of the cavern is about 20 meters (65 feet). Watch your step!
May 6th, 2010
Are Martian gullies formed by water or not? Discover
The idea of liquid water on Mars is an enticing one. We know life on Earth needs liquid water, and if we find it on Mars… We know there’s plenty of frozen water on Mars; we see it there in abundance. But Mars is cold, and the air is thin, making liquid water on the surface difficult to achieve, let alone sustain.
But there’s been tantalizing evidence. Ever since Mars Global Surveyor got to the Red Planet in 1997, we’ve seen gullies sprinkled here and there. These gullies form on slopes near the tops of the hills, and are clearly the result of something moving downslope and digging furrows. But is that something water, or just sand and dust? The conclusions flip-flop back and forth; I’ve seen papers come out saying water-not-sand and others saying sand-not-water several times.
January 26th, 2010
Hello, Red Planet! Discover
If you’ve been outside after it gets dark lately, you may have noticed the brilliant reddish star in the east. But that’s no star; it’s Mars! About every year and a half, the Earth passes Mars as they both orbit the Sun, very much like how a faster racing car on the inside track laps a slower-moving car on the outside track.
When Earth does lap Mars, the Red Planet’s on the opposite side of the sky from the Sun, rising at sunset and setting at sunrise — we say that Mars is at opposition when that happens. When it does, we get two advantages in one: it’s at its closest point, so it’s bigger in telescopes, and it’s up all night so you can observe it at your convenience. This happens next in just a few days, on January 29, 2010.
That’s why the Beauty Without Borders program has set up a Mars observing campaign, to get everyone outside and looking at Mars. If you are part of a local astronomy group, let them know about the campaign, which lasts from tonight, January 25th, through the 30th. Get folks to attend and see Mars through a telescope! It won’t be terribly big like you might see in space probe pictures, of course, but you may catch the polar ice caps, or some other features.
December 22nd, 2009
The blue clouds of the red planet Discover
Emil Kraaikamp is one of the more gifted astrophotographers I’ve seen. He has a 25 cm (10″) telescope that he uses to create truly jaw-dropping views of the sky. Want proof? Check this image out: it’s an animation he made of Mars, using observations he made in early December and showing the planet’s rotation over the course of about 45 minutes (a day on Mars is a half hour longer than Earth’s). You can clearly see both the south and north polar ice caps together with several dark surface features on the planet, which in itself is lovely and very cool. But what blew me away is something you may not notice immediately in the picture. Take a look on the left side of the animation. See those three aligned blue spots, with the one blue spot to the lower right? Those are called orographic clouds, formed when moist air is lifted up over an obstacle; the air cools and the moisture condenses, forming clouds. What kind of obstacle on the Martian surface could do that
April 1st, 2009
Spirit sees phenomenal Martian vista Discover
I’ve been so taken with HiRISE lately that I haven’t written much about the Mars rovers Spirit and Opportunity. They’ve been traversing Mars for almost six years now, taking tons of images and great in situ data. And now I feel remiss, because Spirit has stumbled on something very cool.
These images were taken on Sol 1858, just a few days ago (a Sol is a day on Mars, about a half hour longer than an Earth day). Spirit has been tooling around a high plateau called Home Plate, because it’s shaped like, well, a home plate in baseball. There’s evidence that water flowed in this area a long time ago, and as I looked over the images it was pretty obvious.