March 7, 2023 Image:

Image (Credit): Martian sky. (NASA/JPL-Caltech/MSSS)

The image in this week’s quiz was taken by NASA’s Curiosity Mars rover and shows a feather-shaped iridescent carbon dioxide cloud shortly after sunset on January 27, 2023.

Here is more from NASA:

Studying the colors in iridescent clouds tells scientists something about particle size within the clouds and how they grow over time. These clouds were captured as part of a follow-on imaging campaign to study noctilucent, or “night-shining” clouds, which started in 2021. While most Martian clouds hover no more than 37 miles (60 kilometers) above the ground and are composed of water ice, these clouds appear to be higher in elevation, where it’s very cold. That suggests these clouds are made of carbon dioxide, or dry ice.

February 8, 2023 Image:

Image (Credit): Norther portion of Pluto’s moon Charon. (NASA)

The image in this week’s quiz is a portion of Pluto’s moon Charon. The dark spot in the northern portion is nicknamed “Mordor.”

The entire moon is shown below. Here is NASA’s statement describing what you see:

Remarkable new details of Pluto’s largest moon Charon are revealed in this image from our New Horizons spacecraft taken late on Tuesday from a distance of 289,000 miles (466,000 kilometers). A swath of cliffs and troughs stretches about 600 miles (1,000 kilometers) from left to right, suggesting widespread fracturing of Charon’s crust, likely a result of internal processes. At upper right, along the moon’s curving edge, is a canyon estimated to be 4 to 6 miles (7 to 9 kilometers) deep. Mission scientists are surprised by the apparent lack of craters on Charon. South of the moon’s equator, at the bottom of this image, terrain is lit by the slanting rays of the sun, creating shadows that make it easier to distinguish topography. In Charon’s north polar region, a dark marking nicknamed ‘Mordor’ is prominent in the image. Higher resolution images still to come are expected to shed more light on this enigmatic region.

Note: You were likely to get this quiz right if you had read yesterday’s posted story.

Image (Credit): Pluto’s moon Charon. (NASA)

January 9, 2023 Image:

Image (Credit): Jupiter’s moon Callisto. (NASA)

The image in this week’s quiz is that of Jupiter’s second largest moon Callisto. It is also the third largest moon of the solar system, representing a world that is about the size of the planet Mercury. Here are a few more facts from NASA:

  • Callisto has a heavily cratered surface of ice and rock;
  • NASA’s Galileo spacecraft detected a thin carbon dioxide atmosphere, or exosphere, on Callisto. Later research determined Callisto has hydrogen and oxygen in its atmosphere; and
  • There is evidence of a subsurface ocean on Callisto, putting Callisto on the list of possible places where life could exist beyond Earth.

December 24, 2022 Image:

Image (Credit): First sample tube on the Martian surface. (NASA/JPL-Caltech/MSSS)

The image above is from Mars. It shows 1 of 10 planned tubes of Martian soil being placed on the surface of Mars by the Perseverance rover. This tube was placed on the surface on December 21. The samples will be returned to Earth at some point in the future as part of the Mars Sample Return campaign. You can read more about it here.

Image (Credit): Another image of the sample tube next to the Perseverance Mars rover. (NASA/JPL-Caltech/MSSS)

December 12, 2022 Image:

Image (Credit): South pole on Triton. (NASA)

The image in the quiz is that of Neptune’s largest moon Triton. As noted in a Smithsonian National Air & Space Museum story:

The dark streaks in this image are nitrogen geysers erupting at Triton’s south pole. These geysers extend 26,000 ft (8 km) above Triton’s surface, making them 140 times bigger than Yellowstone’s Old Faithful Geyser.

Triton has seasons that last 40 years, but you would not want to be there for any of it’s seasons. Winter is horribly cold while the summer is full of violent geysers.

Image (Credit): Another view of Triton’s south pole. (US Geological Survey)

November 7, 2022 Image:

Image (Credit): The Richat Structure in Mauritania. (NASA)

The image above was captured by the International Space Station on August 21, 2022. It is the Richat Structure, also called “Eye of the Sahara,” located in Mauritania. While it may look like an impact crater, it is actually an eroded geological dome.

Below is what could be another eroded geological dome, also photographed by the ISS, but this time in the United States. Called Upheaval Dome, scientists are still discussing whether the crater was created by a salt dome or a meteor.

Image (Credit): Upheaval Dome in Canyonlands National Park. (Earth Science and Remote Sensing Unit, NASA Johnson Space Center)

October 2, 2022 Image:

Image (Credit): China’s Tanggula Mountains as viewed from the ISS. (ESA)

The image above was taken by European Space Agency astronaut Samatha Cristoforetti aboard International Space Station (ISS). From a height of 260 miles, it shows China’s Tanggula Mountains near Hala Lake. You may have thought it was an image from the surface of Mars. You can find more ISS crew observations here.

September 7, 2022 Image:

Image (Credit): A Chinese space probe on the Moon. (China National Space Administration/AFP Via Getty Images)

The image above shows the China National Space Administration’s (CNSA) Chang’E-5 lander probing the Moon’s surface back in December 2020. The mission returned about 60 ounces of soil and rock samples containing evidence of water from the lunar surface. You can read more about the mission here.

Image (Credit): CNSA’s Chang’e-5 spacecraft captured this image of the lunar surface shortly after landing in the Ocean of Storms on 1 December 2020. (CNSA/Chinese Lunar Exploration Program)

August 15, 2022 Image:

Image (Credit): Surface of Uranus’ moon Miranda. (NASA/JPL)

The image above shows the Uranian moon Miranda, taken by the NASA’s Voyager 2 spacecraft on Jan. 24, 1986. It is much smaller than our Moon (only one-seventh the size), though it has canyons that can be about 12 times deeper than those in the Grand Canyon. You can read more about Miranda here.

Image (Credit): Uranus’ moon Miranda, as seen by Voyager 2. (U.S. Geological Survey/NASA/JPL)

July 8, 2022 Image:

Image (Credit): Shanghai Astronomy Museum. (Ennead)

The image above shows the Shanghai Astronomy Museum, which opened to the public in 2021. The museum architect website notes:

At 420,000 square feet, the new astronomical branch of the Shanghai Science and Technology Museum will be the largest museum worldwide solely dedicated to the study of astronomy.

Image (Credit): Shanghai Astronomy Museum. (Ennead)

June 7, 2022 Image:


The image above shows the asteroid Vesta and is from NASA’s Dawn mission to both Vesta and the dwarf planet Ceres. The Dawn spacecraft left Earth on  September 27, 2007 and started its orbit of Vesta on July 16, 2011. The spacecraft studied the asteroid for 14 months. About 326 miles in diameter, Vesta is believed to be the largest object in the asteroid belt after Ceres.

The image itself is described by NASA in this way:

This image from the atlas of the giant asteroid Vesta was created from images taken as NASA’s Dawn spacecraft flew around the protoplanet. The set of maps was created from mosaics of 10,000 images from Dawn’s framing camera instrument, taken at a low altitude of about 130 miles (210 kilometers).

Image (Credit): This mosaic synthesizes the best views that NASA’s Dawn spacecraft had of giant asteroid Vesta. Dawn studied Vesta from July 2011 to September 2012.

May 3, 2022 Image:

Credit: ESA/DLR/FU Berlin, CC BY-SA 3.0 IGO

The image above comes from the surface of Mars as captured by the European Space Agency’s (ESA) Mars Express. It shows ice-related features within the Martian Utopia region, which holds the largest known impact basin in the entire Solar System. Here is more from ESA:

Utopia is one of three major basins in Mars’ northern hemisphere (along with Acidalia and Arcadia) and has a diameter of roughly 3 300 km: just under twice the north-south size of Earth’s Sahara Desert.

This image shows a slice of Utopia Planitia, the plain that fills this colossal and ancient basin.

This plain is thought to have formed as the Utopia basin was filled by a mix of sediments, lavas and volatile substances (those that vaporise easily, such as nitrogen, carbon dioxide, hydrogen and water), all transported across the martian surface by water, wind or other processes.

…the two largest impact craters visible here are surrounded by double-layered mounds of material. A similarly layered appearance is also visible in the deposits that have built up within the craters themselves, and in the craters’ thick rims.

April 15, 2022 Image:


The image above from NASA shows collapsed volcanoes that have formed large, dark spots on Io’s surface. Io is Jupiter’s third largest moon. Jupiter’s has 79 moons. NASA noted:

Io is the most volcanically active body in the solar system. Io’s surface is covered by sulfur in different colorful forms. As Io travels in its slightly elliptical orbit, Jupiter’s immense gravity causes “tides” in the solid surface that rise 300 feet (100 meters) high on Io, generating enough heat for volcanic activity and to drive off any water. Io’s volcanoes are driven by hot silicate magma.

Image (Credit): A volcanic explosion on Io. (NASA/JPL/University of Arizona)

March 2, 2022 Image:

Credit: NASA

The image above is a photo taken by NASA’s Mars rover Curiosity, as NASA explains:

Using an onboard focusing process, the Mars Hand Lens Imager (MAHLI) aboard NASA’s Mars rover Curiosity created this product by merging two to eight images previously taken by the MAHLI, located on the turret at the end of the rover’s robotic arm.

The official Curiosity rover tweet describes the content of the image:

I spy with my hand-held imager (MAHLI) this beautiful, fragile and tiny feature. It’s a concretion, eroded from sedimentary rock that was cemented by mineral-rich groundwater. Size? Just 1 cm.

February 4, 2022 Image:

Credit: SARAO

The strange picture above is a new MeerKAT radio telescope image of the center of the Milky Way Galaxy. Here is the story:

The image captures radio emission from numerous phenomena, including outbursting stars, stellar nurseries, and the chaotic region around the 4 million solar mass supermassive black hole that lurks in the centre of our Galaxy, 25,000 light-years from Earth. Radio waves penetrate the intervening dust that obscures the view of this region at other wavelengths. MeerKAT’s innovative design, sensitivity, and geographical vantage point have been the keys to producing the remarkable image, which reveals new supernova remnants – the expanding shells of material left behind when massive stars end their lives explosively – including a rare almost-perfect spherical example, and provides astronomers with the best insight yet into the population of mysterious ‘radio filaments’ found nowhere else.

Here is the full press release from the South African Radio Astronomy Observatory (SARAO) discussing various aspects of this image.

January 17, 2022 Image:

Credit: CNN

The image above is the Hunga-Tonga-Hunga-Ha’apai volcanic eruption from late last week. According to NASA, the eruption in the Pacific Ocean caused quite a stir throughout the world:

On January 14, the Volcanic Ash Advisory Center Wellington (VAAC) reported a very large eruption at Hunga Tonga-Hunga Ha’pai, based on satellite imagery. At that time, the steam obscured the ash plume and the height of the ash plume was unknown. According to the Global Alert and Disaster Coordination System (GDACS), a 5.8 magnitude earthquake was registered from Tonga on that day, at a depth of 5 km, with 800,000 people within 100 km of the quake.

By the morning of January 15, GDACS recorded a second large earthquake (4.5 magnitude) and the volcano exploded in a “major vent-clearing event”, according to a report from ABC NEWS in Australia. The eruption was heard in New Zealand, 1,300 miles away, and Alaska, which sits roughly 6,000 miles away. The powerful explosion—made even stronger by sizzling hot magma reacting with cold ocean water—triggered a tsunami. Waves washed over nearby islands, knocking down communication lines, flooding coastlines, and forcing evacuations from low-lying areas. Australia offered to send reconnaissance flights over Tonga’s islands to assess damage, but as of late on January 15, the thick plume of ash prevented such flights from occurring.

Tsunami waves coursed across the vast Pacific Ocean, bringing surges of more than 3 feet to Alaska, coastal flooding in California, and smaller surges in Oregon, Washington State, British Columbia, Mexico, South America, Hawaii, and Japan. By the late evening of January 15, tsunami warnings had been downgraded or cancelled along most of the Pacific basin. Some speculate that the January 15 eruption was among the strongest in the 21st century—a theory that will be tested as scientists sort through data and damage estimates over the next few weeks or months.

Of course, volcanoes can be found throughout the solar system, including on Mars, Venus, and the moons of Jupiter and Saturn. Dwarf planets, including Pluto and Ceres, are also believed to have volcanoes. The image below is an apparent ice volcano on Ceres called Ahuna Mons. The image is from NASA’s Dawn spacecraft taken in December 2015 about 240 miles above the surface.

Image (Credit): Ceres volcano discussed in “The Mystery of Ahuna Mons, the Lonely Ice Volcano.” (University of Arizona)