Mercury's Caloris Basin
Caloris is about miles (1, kilometers) across and is ringed by mile-high mountains. For scale, the state of Texas is miles (1, kilometers) wide from east to west. Original Caption. This mosaic of Caloris basin is an enhanced-color composite overlain on a monochrome mosaic featured in a previous post. The color mosaic is made up of images obtained when both the spacecraft and the Sun were . Caloris is one of the youngest large multiring basins. It probably was formed at the same time as the last giant basins on the Moon, about billion years ago. On the other side of the planet, exactly opposite Caloris, is a region of weirdly contorted terrain. It likely formed at the same time as the Caloris impact by the focusing of seismic waves from that event.
Calorisprominent multiringed impact basin on Mercury. The ramparts of Caloris are about 1, km miles across. Its interior contains extensively ridged and fractured plains. The largest ridges are a few hundred kilometres long. Two types of terrain surround Caloris—the rim and the ejecta terrains.
The rim is a ring of irregular mountains almost 3 km 2 miles in height, the highest mountains yet seen on Mercury. A second, much smaller escarpment ring stands beyond the first.
Smooth plains occupy the depressions between mountains. Beyond the outer escarpment is a zone of linear radial ridges and valleys that are partially filled by plains. Volcanism played a prominent role in forming many of these plains. Caloris is bwsin of the youngest large multiring basins. It gasin was formed at how to produce saliva for testing same time as the last giant basins on the Moonabout 3.
On the other side of the planetexactly opposite Caloris, is a region of weirdly contorted terrain. It likely formed at the same time as the Caloris impact by the focusing of seismic waves from that event.
Additional Info. More About Contributors Article History. Home Science Astronomy Caloris impact basin, Mercury. Print Cite verified Cite. While every effort has been made to follow citation style rules, there may be some discrepancies. Please refer to the appropriate style manual or other sources if you have any questions.
Facebook Twitter. Give Feedback External Websites. Let us know if si have suggestions to improve this article requires login. External Websites.
Clark R. See Article History. The Caloris Basin in yellow on Mercury, as seen from the Messenger spacecraft, Read More on This Topic. The ramparts of the Caloris impact basin span a diameter of about 1, km miles. Its interior is occupied by smooth Caloris Basin, Mercury, one of the largest impact basins in the solar system.
Hilly and lineated terrain located diametrically across Mercury from Caloris, imaged by Mariner 10 in Seismic waves from the giant impact that formed Cloris are thought to have been focused on this area, disrupting preexisting craters and plains. The smooth interior of the large crater on the left indicates that its floor filled in sometime after the impact.
Get a Britannica Premium subscription and gain access to exclusive content. Subscribe Now. Learn More in these related Britannica articles:. Its interior is occupied by smooth plains that are extensively ridged and fractured in a prominent radial and concentric pattern.
The what is the caloris basin basim are…. Multiringed basinany of a class of geologic features that have been observed on various planets and satellites in the solar system.
The outer rings of the basins are clifflike scarps that…. Mercurythe innermost planet of the solar system and the what is the location of mount everest in size and mass. Its closeness to the Sun and its smallness make it the most elusive of the planets visible to the unaided eye.
History at your fingertips. Sign up here to see what happened On This Dayevery day in your inbox! Email address. By signing up, you agree to our Privacy Notice. Be on the lookout for your Britannica newsletter to get trusted stories delivered right to your inbox.
You might also be interested in:
This mosaic of Caloris basin is an enhanced-color composite overlain on a monochrome mosaic featured in a previous post. Caloris Planitia /k??l??r?s pl??n??(i)?/ is a plain within a large impact basin on Mercury, informally named Caloris, about 1, km ( mi) in diameter. It is one of the largest impact basins in the Solar System. "Calor" is Latin for "heat" and. The Caloris Basin is the largest feature on the surface of Mercury. This crater was formed by the impact of a large meteorite in the early formation of the solar system. We only know what half of the crater looks like, because the other half was in darkness when Mariner 10 flew by the planet. Surrounding the impact site are concentric ridges within relatively smooth plains probably brought about by .
When Mariner 10 flew past Mercury, it caught an immense impact basin lying half in and half out of sunlight, which they named Caloris. Even with only half the basin visible, scientists knew it was one of the largest in the solar system. Geologists had to wait more than 25 years to see the rest of Caloris, and when they did it turned out to be even bigger than they had thought.
But the fact that Caloris was only half in sunlight was fortuitous in one sense, because it meant that the spot on Mercury that was exactly opposite the area of the Caloris impact was also partially in sunlight. That spot looks weird.
In fact, this area has been referred to since Mariner 10 as the "weird terrain" on Mercury. But why should terrain antipodal to Caloris look unusual? It represents the spot on Mercury that is as far as you can get from the impact site, so it seems like the spot that would be least affected by a giant impact. Surprisingly, the opposite is true: the point on Mercury that's farthest from the Caloris impact actually gets magnified effects; it's worse to be degrees away from an impact than it is to be degrees away.
There are two reasons why; one comes from above, and the other from below. The first has to do with where the ejecta flies. Ejecta from an impact travels outward in all directions, on roughly ballistic trajectories. For small impacts, those ballistic trajectories result in a splash-like deposit around the crater, a widening circle of deposits.
But if the impact has enough energy, the material can go so far around the spherical planet that the ballistic trajectories start to converge again. You can actually see an example of this on Mercury, with the bright rays of the crater Hokusai separating and then converging again as they nearly meet at a spot antipodal to the impact. And that impact didn't even make a very big crater; the convergent crashing of the ejecta from Caloris would have been huge.
Ejecta travels above an impact. Below the impact, you get shock waves, which are very much like earthquake waves specifically, the compression type of earthquake waves called P waves. A shock wave travels outward in all directions, and if that's all that happened there would be nothing special about the antipodal point.
But waves, just like light, sound, and water waves, reflect and refract whenever they reach boundaries between two materials. For Mercury there's two key boundaries: the boundary between planet and space that is, the surface , and the boundary between the solid mantle and molten outer core. As the shock waves reflect from the surface, they bounce right around the planet to converge at the antipode.
What's more, when the shock waves go from mantle to molten core, they slow down, refracting in a way that tends to focus them at the antipode; in a way, Mercury's core acts as a giant lens, focusing the shock waves to a spot antipodal to the impact site.
The waves interfere constructively, piling on top of each other to shake the ground with much higher energy at the antipode than just a few degrees away from it. This has actually been recorded on Earth, although it's rare. Seismic stations antipodal to large earthquakes have recorded larger than expected ground shaking. Detection is rare for several reasons. For one thing, Earth isn't a perfect sphere, so the convergence isn't perfect.
Also, you have to be really close to degrees away from the original earthquake, and the odds aren't great for there to be seismic stations located within two degrees of the antipodal point to a great big earthquake. It doesn't help that vast majority of land on Earth has ocean at the antipodal point. Here's a well-written term paper by R. Brian White that explains all this in more detail, with diagrams showing the converging paths of the earthquake waves.
<- What does a b s mean - How to read a xls file->