New Mexico is known for its otherworldly landscapes - but Kilbourne Hole, a volcanic crater located southwest of Las Cruces, is so otherworldly that NASA sent astronauts there to train for missions to the moon. Read on to learn more about this intriguing landform and New Mexico's role in astronaut training.

The Kilbourne crater is a remnant of an ancient volcanic explosion.

Kilbourne Hole is a special type of volcanic crater called a maar. This type of crater forms when underground water comes in contact with hot lava, or magma, and causes a steam explosion. Unlike other types of volcanoes, maars leave a depression in the earth instead of an above-ground rim.

Views from above give you an idea of the vast size of the crater.

The elliptical crater is more than 1.7 miles long, one mile wide, and 300 feet deep. It is part of a larger volcanic region called the Potrillo Volcanic Field that has additional maars and other types of volcanoes.

Between 1969 and 1971 Apollo astronauts trained at Kilbourne Hole.

Crews from Apollo 12 through 17 trained at the Kilbourne Hole. There, they performed field geology exercises like perfecting their mapping techniques and becoming familiar with their equipment. Dick Gordon (while serving as backup commander for Apollo 15), is shown here at the base of the Kilbourne crater. (Gordon had already flown to the moon as Command Module Pilot with Apollo 12.)

Apollo astronauts trained all over New Mexico.

As well as Kilbourne Hole, NASA sent astronauts to locations all over New Mexico for training. Some of these spots include the Capulin Mountains, Philmont Scout Ramp (near Cimarron), and the Valles Caldera. This photo shows Apollo 15 astronauts, Dave Scott (right) and Jim Irwin (left) driving the Geologic Rover (or Grover) along the rim of the Rio Grande Gorge, near Taos.

Kilbourne Hole Volcanic Crater became a National Natural Landmark in 1975.

The National Landmark program recognizes locations that have the "best" of something. For example, Kilbourne Hole represents the best example of a maar. The program also seeks to preserve theses sites so others can study and learn from them.

The crater is a haven for rockhounds and geology junkies.

There are a lot of interesting rocks and minerals at the crater. When Kilbourne exploded, chunks of rock, or volcanic bombs, were thrown into the air and rained back down. Though they may look black or brown on the surface, they contain yellow and green olivine crystals. Just a note -- check with BLM before removing anything from the site.

Kilbourne Crater is open to the public.

Just park on the rim and hike on in. For directions and more information about visiting Kilbourne Hole visit the Bureau of Land Managment.

Who's explored the Kilbourne crater? Anyone planning a trip now that you know about it? Let us know your thoughts.