What is found inside the Tycho crater

Discovering the Secrets Inside Tycho Crater

For part of each lunation, Tycho Crater stands out as the most noticeable feature on the Moon.

Named after the Danish astronomer Tycho Brahe (1546-1601), whose precise measurements of Mars’ movements helped Johannes Kepler prove that planets orbit in ellipses, not circles, Tycho Crater has a rich history.

Tycho Brahe was born on December 14, 1546, in Knudstrup, Scania, Denmark, and passed away on October 24, 1601, in Prague.
Tycho Brahe was born on December 14, 1546, in Knudstrup, Scania, Denmark, and passed away on October 24, 1601, in Prague.

What sets Tycho Crater apart is its high, continuous wall and striking central peak. But its most remarkable feature is its extensive system of bright rays. These rays extend outward in all directions, covering more than 550,000 square kilometers. They also contain dense clusters of small secondary crater pits, making Tycho Crater truly unique.

Tycho Crater: A Lunar Landmark

Facts About Tycho Crater

  • Size: 86 km
  • Age: Over 100 million years
  • Location: Latitude 43.3°S, longitude 11.2°W
  • Recommended observing equipment: 4-inch telescope

At sunrise, Tycho Crater appears as a normal crater, with its floor partly in shadow and sunlight highlighting the central peak. However, as the day progresses, the rays become visible. Near the full Moon, these rays dominate the scene, covering everything they cross and making even large craters difficult to identify.

Tycho Crater’s Distinctive Features

Tycho lies in the southern uplands, often giving the impression of being a polar crater. However, it is well clear of the libration zone and is only slightly foreshortened.

The rays of Tycho overlay other features, indicating that the crater is very young by lunar standards—possibly the youngest of all major craters. Its age is estimated to be a little over 100 million years.

Theories About Tycho’s Impactor

It has been suggested that the impactor that created Tycho was a fragment from the asteroid 298 Baptistina. Some theories even propose that another fragment from the same asteroid produced the Chicxulub crater 65 million years ago, leading to the demise of the dinosaurs.

Tycho’s Surrounding Area

Tycho is located in a crowded area, surrounded by large craters such as Street, Pictet, and Sasserides. Despite this, it is always easy to spot due to its bright walls and regular shape.

When the rays come into view, they appear to extend from the walls rather than the central peak.

The ramparts beyond the rim are darker than the floor, extending out to a distance of at least 100 km, and are free of rays. This darker rim may consist of minerals dislodged during the impact.

A Dramatic Sunrise View Captured by LRO

On June 10, 2011, the LRO spacecraft slewed 65° to the west, allowing the LROC NACs to capture a dramatic sunrise view of Tycho Crater. A popular target for amateur astronomers, Tycho is located at 43.37°S, 348.68°E, and spans approximately 82 km (51 miles) in diameter. The summit of the central peak rises 2 km (6562 ft) above the crater floor, which itself is about 4700 m (15,420 ft) below the rim. Numerous “clasts,” ranging in size from 10 meters to hundreds of meters, are exposed on the slopes of the central peak.

Were these distinctive outcrops formed by the crushing and deformation of the target rock as the peak grew? Or do they represent preexisting rock layers that were brought intact to the surface? Imagine future geologists carefully making their way across these steep slopes, sampling a variety of rocks that have been brought up from deep within the Moon.

The Youthful Sharpness of Tycho Crater

Tycho’s steep and sharp features are due to its relatively young age of about 110 million years. Over time, micrometeorites and larger meteorites will gradually grind and erode these steep slopes, transforming them into smoother mountains.

Captivating View of Tycho Crater

The LROC WAC mosaic of Tycho Crater, captured with lighting similar to the NAC oblique image, showcases the crater's dramatic features. This mosaic spans 130 km in width, with north at the top. [Credit: NASA/GSFC/Arizona State University]
The LROC WAC mosaic of Tycho Crater, captured with lighting similar to the NAC oblique image, showcases the crater’s dramatic features. This mosaic spans 130 km in width, with north at the top. [Credit: NASA/GSFC/Arizona State University]

Fascinating Details of Tycho Crater’s Central Peak

A NAC pair acquired on May 27, 2010, provides an excellent straight-down view of Tycho Crater’s summit, including the large boulder featured in today’s image. The fractured impact melt deposit surrounding the boulder is also visible. Is the smooth area on top of the boulder frozen impact melt?

The large boulder of Tycho crater. A vertical view of Tycho Crater's central peak summit reveals the same 120-meter-wide boulder. [Credit: NASA/GSFC/Arizona State University]
A vertical view of Tycho Crater’s central peak summit reveals the same 120-meter-wide boulder. [Credit: NASA/GSFC/Arizona State University]

These LROC images reveal that the central peak formed rapidly, with impact melt thrown straight up during the impact and falling back down, creating “instant mountains.” Alternatively, the melt may have arrived through a different mechanism. The fractures likely formed over time as the steep walls of the central peak slowly eroded and slipped downhill. Eventually, the peak will erode back, causing the large boulder to slide 2000 meters to the crater floor.

Topographic Model of Tycho Crater

A topographic model of Tycho Crater, derived from LROC WAC stereo images, covers the same area as the WAC mosaic shown above. [Credit: NASA/GSFC/Arizona State University]
A topographic model of Tycho Crater, derived from LROC WAC stereo images, covers the same area as the WAC mosaic shown above. [Credit: NASA/GSFC/Arizona State University]

Intricate Surface of Tycho Crater’s Floor

The bottom of Tycho Crater is strewn with blocks, boulders, and impact melt textures. These impact melt deposits often display networks of fractures, visible even at the LROC WAC pixel scale of 100 meters. At NAC resolution, with very high incidence angles (illuminated almost along the horizon), the surface’s extremely complicated and chaotic nature is striking.

The floor of Tycho Crater is covered in many places by a chaotic surface of impact melt forms. The image, with a scale of 0.5 m/pixel and a width of 500 meters, was taken at an incidence angle of 84°, with sunlight coming from the left. [Credit: NASA/GSFC/Arizona State University]
The floor of Tycho Crater is covered in many places by a chaotic surface of impact melt forms. The image, with a scale of 0.5 m/pixel and a width of 500 meters, was taken at an incidence angle of 84°, with sunlight coming from the left. [Credit: NASA/GSFC/Arizona State University]

Complex Thermal Histories of Impact Melts

Impact melts have extremely complex thermal histories. When a meteoroid’s kinetic energy is high enough, the initial temperature of an impact melt can far exceed that of normal magma from volcanic activity. These melts mix with ejecta debris, flow down slopes, and form puddles, losing heat and increasing in viscosity over time.

Once settled on the crater floor, solidification begins at the top and bottom (forming chilled margins) and gradually progresses inward. Any deformation during this time—such as the isostatic rebound of the crater floor, uneven thermal contraction, or late flows pushing against pre-existing melts—disturbs the solidifying surfaces. This creates chaotic patterns and can sometimes cause local “eruptions” of melt onto the newly solidified layer.

Detailed View of Tycho Impact Crater

The LROC WAC 100 m/pixel mosaic of Tycho impact crater cavity is overlaid by a WAC color DTM at 500 m/pixel (DLR, Germany). The image center is approximately at latitude 43.32°S, longitude 11.25°W. The blue box and yellow star indicate the locations of the NAC frame and today's featured image. [Credit: NASA/GSFC/Arizona State University]
The LROC WAC 100 m/pixel mosaic of Tycho impact crater cavity is overlaid by a WAC color DTM at 500 m/pixel (DLR, Germany). The image center is approximately at latitude 43.32°S, longitude 11.25°W. The blue box and yellow star indicate the locations of the NAC frame and today’s featured image. [Credit: NASA/GSFC/Arizona State University]

Tycho Crater: A Young and Prominent Feature

Tycho is a young and prominent rayed crater on the lunar nearside. The impact that formed Tycho crater ejected a large mass of impact melt to its north side, creating a series of beautiful flow patterns. This melt pooled in several topographic lows, and as it cooled, the upper crusts fractured, often forming polygonal patterns.

Polygonal Fractures on Tycho Crater’s Impact Melt

Polygonal fractures are visible on a flow lobe of impact melt splashed out of Tycho Crater. The image scale is 0.52 meters per pixel, with an incidence angle of 69.1°. Sunlight illuminates the scene from the left. [Credit: NASA/GSFC/Arizona State University]
Polygonal fractures are visible on a flow lobe of impact melt splashed out of Tycho Crater. The image scale is 0.52 meters per pixel, with an incidence angle of 69.1°. Sunlight illuminates the scene from the left. [Credit: NASA/GSFC/Arizona State University]

Intriguing Polygonal Fractures in Tycho Crater’s Impact Melt

The image reveals a set of crisply preserved polygonal fractures. Small chains of pits are also visible alongside these fractures. Are these pits nascent fractures that never fully developed? Or perhaps partially collapsed tubes through which melt once flowed? If the latter, could there be open passages that astronauts might one day venture into and explore?

Color-Coded Mosaic of Tycho Crater

The LROC WAC 100 m/pixel mosaic around Tycho Crater is overlaid by a WAC color-coded DTM at 500 m/pixel (DLR, Germany). The image center is at 43.3°S latitude, 348.6°W longitude. The blue box and yellow star indicate the locations of today's full featured image. [Credit: NASA/GSFC/Arizona State University]
The LROC WAC 100 m/pixel mosaic around Tycho Crater is overlaid by a WAC color-coded DTM at 500 m/pixel (DLR, Germany). The image center is at 43.3°S latitude, 348.6°W longitude. The blue box and yellow star indicate the locations of today’s full featured image. [Credit: NASA/GSFC/Arizona State University]

Impact Melt Features in Tycho Crater’s Floor

Tycho Crater’s floor showcases a variety of impact melt features. These include chaotic surfaces, polygonal fractures, and smooth areas where the melt has pooled and solidified. The complexity and diversity of these features provide valuable insights into the crater’s formation and thermal history.

Depressions and Positive Relief Features in Tycho Crater

Depressions and positive relief features in Tycho Crater were formed by a complex mixture of granular material and impact melt settling on the floor. The image width is 370 meters, captured by LROC NAC M119923147L. [Credit: NASA/GSFC/Arizona State University]
Depressions and positive relief features in Tycho Crater were formed by a complex mixture of granular material and impact melt settling on the floor. The image width is 370 meters, captured by LROC NAC M119923147L. [Credit: NASA/GSFC/Arizona State University]

Diverse Features Created by Impact Melt on the Moon

Impact melt creates a wide variety of features on the Moon, including melt ponds, draped ejecta, viscous flows, linear and nonlinear depressions, and positive relief features. As impact melts mix with loose rock during crater formation, solid pieces of rock protrude above the surface of the ponding melt, forming small peaks (positive relief features). The depressions may be cooling fractures in the melt, resulting from slow solidification and contraction, unlike the behavior of water when it freezes. Alternatively, they could be part of an impact melt drainage network. The exact origins of these features remain uncertain. The best way to uncover their secrets is to have astronauts explore and traverse this terrain on the Moon.

Location of Melt Features in Tycho Crater

The LROC WAC mosaic highlights the location of the melt features within Tycho Crater, as seen in the NAC image above. The image width is 150 km. [Credit: NASA/GSFC/Arizona State University]
The LROC WAC mosaic highlights the location of the melt features within Tycho Crater, as seen in the NAC image above. The image width is 150 km. [Credit: NASA/GSFC/Arizona State University]

Ejecta in Tycho Crater

Ejecta in Tycho Crater showcases a complex landscape shaped by the impact event. This material, thrown out during the crater’s formation, includes fragmented rock, melt deposits, and varied surface textures. These ejecta deposits provide critical insights into the impact processes and the Moon’s geological history.

Massive Ejecta Block in Tycho Crater

A 320-meter block of ejecta in Tycho Crater is covered by a thin layer of impact melt. The image, captured by LROC NAC 142334392RE, has a width of 370 meters. [Credit: NASA/GSFC/Arizona State University]
A 320-meter block of ejecta in Tycho Crater is covered by a thin layer of impact melt. The image, captured by LROC NAC 142334392RE, has a width of 370 meters. [Credit: NASA/GSFC/Arizona State University]

Tycho Crater: A Prominent Copernican Age Feature

The rays are so widespread that Apollo 17 astronauts collected samples of its ejecta over 2000 km away from the crater. These samples have been dated to about 110 million years old. Additionally, surface views of Tycho’s ejecta blanket were captured by the Surveyor 7 soft lander.

Context Mosaic of Tycho Crater

The LROC WAC context mosaic of Tycho Crater highlights the ejecta block within Tycho, indicated by an arrow. The image width is 150 km. [Credit: NASA/GSFC/Arizona State University]
The LROC WAC context mosaic of Tycho Crater highlights the ejecta block within Tycho, indicated by an arrow. The image width is 150 km. [Credit: NASA/GSFC/Arizona State University]

Smooth Areas on Tycho Crater’s Ejecta Block

Notice the smooth areas on the top of the ejecta block in this NAC frame. This smooth surface is likely a thin sheet of impact melt. The large block was probably ejected during the impact event, then fell back into the crater and was subsequently covered by impact melt. These events must have occurred swiftly after the impact, as the melt would solidify shortly after forming.

Discover More with the Right Telescope

Best telescop

Tycho Crater offers a fascinating glimpse into the Moon’s dynamic history. From its dramatic central peak to the intricate patterns of its impact melt, Tycho continues to captivate astronomers and space enthusiasts alike. Observing these features can be incredibly rewarding with the right equipment.

For those looking to explore Tycho Crater and other lunar wonders up close, having a quality telescope is essential. Check out our guide to the best telescopes to find the perfect instrument for your stargazing adventures.

Whether you’re an amateur astronomer or a seasoned observer, Tycho Crater is a testament to the Moon’s enduring mysteries, waiting to be discovered. Happy stargazing!

Scroll to Top