moons Archives

March 7, 2024March 7, 2024 by Evan Gough

Perseverance Sees Phobos, Deimos and Mercury Passing in Front of the Sun

NASA's Perseverance Mars rover used its Mastcam-Z camera to capture the silhouette of Phobos, the larger of Mars' pair of moons, as it passed in front of the Sun on Feb. 8, 2024, the 1,056th Martian day, or sol, of the mission. Image Credit: NASA/JPL-Caltech/ASU/MSSS/SSI

NASA’s Perseverance rover is busy exploring the Martian surface and collecting samples for eventual return to Earth. But the rover recently took some time to gaze upward and observe the heavens. Using Mastcam-Z, the rover’s primary science camera, Perseverance captured Phobos, Deimos, and Mercury as they transited in front of the Sun.

March 1, 2024March 1, 2024 by Evan Gough

How Warm Are the Oceans on the Icy Moons? The Ice Thickness Provides a Clue.

Jupiter's moon Ganymede is the largest moon in the Solar System and may have an ocean sandwiched between two layers of ice. But how warm is that ocean? Image Credit: By National Oceanic and Atmospheric Administration Public Domain, https://commons.wikimedia.org/w/index.php?curid=8070396

Scientists are discovering that more and more Solar System objects have warm oceans under icy shells. The moons Enceladus and Europa are the two most well-known, and others like Ganymede and Callisto probably have them too. Even the dwarf planet Ceres might have an ocean. But can any of them support life? That partly depends on the water temperature, which strongly influences the chemistry.

We’re likely to visit Europa in the coming years and find out for ourselves how warm its ocean is. Others on the list we may never visit. But we may not have to.

February 27, 2024February 27, 2024 by Evan Gough

New Moons Found at Uranus and Neptune

The discovery image of the new Uranian moon S/2023 U1 using the Magellan telescope on November 4, 2023. Uranus is just off the field of view in the upper left, as seen by the increased scattered light. S/2023 U1 is the faint point of light in the center of the image with the yellow arrow. The trails are from background stars. Credit: Scott Sheppard.

Astronomers have found three new moons orbiting our Solar System’s ice giants. One is orbiting Uranus, and two are orbiting Neptune. It took hard work to find them, including dozens of time exposures by some of our most powerful telescopes over several years. All three are captured objects, and there are likely more moons around both planets waiting to be discovered.

February 13, 2024February 16, 2024 by Matt Williams

Venus “Quasi-moon” Just Got a Name. Henceforth, it Shall be Called Zoozve.

The children’s poster of the Solar System that features Zoozve, Venus's quasi-moon. Credit: Alex Foster/Latif Nasser

Ask any astronomer, and they will tell you that all of the planets in the Solar System (including those “dwarf planets”) have satellites, with the exception of Mercury and Venus. However, that is not entirely the case, as Venus has what is known as a “quasi-moon” – a large asteroid that orbits the planet but is not gravitationally bound to it. In 2002, astronomer Brian Skiff discovered this body using the Discovery Telescope at the Lowell Observatory (where Clyde Tombaugh discovered Pluto). Until recently, this object was known by its official designation, 2002VE₆₈.

However, on February 5th, 2024, the International Astronomical Union (IAU) conferred a new name for the object: Zoozve. The name was announced in a bulletin (vol. 4, no. 5) issued by the IAU’s Working Group for Small Bodies Nomenclature (WGSBN). The IAU, which is responsible for naming celestial objects, traditionally prefers to assign names that come from mythological traditions to objects that cross Earth’s orbit. But in this case, the origins of Zoozve’s strange name are more of (to quote Bob Ross) a “happy accident,” where a children’s poster that showed the object led to a conversation and an official request.

January 29, 2024January 30, 2024 by Evan Gough

Did We Find Exomoons or Not? The Question Lingers.

Does Kepler-1708b have an exomoon? Scientists disagree. Image Credit: NASA

Do exoplanets have exomoons? It would be extraordinary if they didn’t, but as with all things, we don’t know until we know. Astronomers thought they may have found exomoons several years ago around two exoplanets: Kepler-1625b and Kepler-1708b. Did they?

December 11, 2023December 11, 2023 by Evan Gough

Exomoons Defy Discovery

So far we only know of two exoplanets with candidate exomoons. But even those two may be false positives. Image Credit: NASA

For a long time, we wondered if other stars hosted planets like the Sun does. Finally, in the 1990s, we got our answer. Now, another question lingers.

Most of the planets in our Solar System have moons. Do exoplanets have exomoons?

October 26, 2023October 26, 2023 by Evan Gough

JWST Takes a Detailed Look at Jupiter’s Moon Ganymede

Juno captured this image of Ganymede in July 2022. Now the JWST is taking a look at our Solar System's largest moon. Image Credit: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Nature doesn’t conform to our ideas of neatly-contained categories. Many things in nature blur the lines we try to draw around them. That’s true of Jupiter’s moon Ganymede, the largest moon in the Solar System.

The JWST took a closer look at Ganymede, the moon that’s kind of like a planet, to understand its surface better.

October 25, 2023October 25, 2023 by Evan Gough

Io has 266 Active Volcanic Hotspots Linked by a Global Magma Ocean

NASA’s Galileo spacecraft captured this image of a volcanic eruption on Io in 1997. Image Credit:NASA, NASA-JPL, DLR

Jupiter’s Io stands apart from the Solar System’s other moons, with its numerous volcanoes and its surface dominated by lava flows. Io’s surface volcanism was confirmed in 1979 when the Voyager spacecraft imaged it, but its volcanic nature isn’t duplicated anywhere else in our system. Tidal heating is behind the moon’s eruptive nature, driven by Jupiter’s powerful gravity, and by resonance with other moons. But is there a magma ocean inside Io?

A final answer to that question has been elusive, but new research supports the idea of a magma ocean.

October 19, 2023October 19, 2023 by Evan Gough

Juno Completes its Closest Flyby of Io Yet

Not since the Galileo mission ended 20 years ago have we seen such great images of Io. NASA's Juno spacecraft captured this image with its JunoCam instrument on October 15th from less than 12,000 km altitude. Ted Stryk processed the image. Image Credit: Ted Stryk/NASA/JPL-Caltech/SwRI/MSSS/

Jupiter’s ocean moons capture most of our attention because of their potential habitability. But Io, Jupiter’s bad-boy volcanic moon, is in a class of its own. There’s nothing else like it in the Solar System, and NASA’s Juno spacecraft captured new images of the volcanic satellite during its closest approach yet.

September 28, 2023September 28, 2023 by Evan Gough

Colliding Moons Might Have Created Saturn’s Rings

Saturn's rings are arguably the most recognizable feature in our Solar System and are made mostly of ice particles. New research says a collision between icy moons may have created them in the recent past. Image Credit: NASA/JPL/Space Science Institute

If we could wind the clock back billions of years, we’d see our Solar System the way it used to be. Planetesimals and other rocky bodies were constantly colliding with each other, and new objects would coalesce out of the debris. Asteroids rained down on the planets and their moons. The gas giants were migrating and contributing to the chaos by destroying gravitational relationships and creating new ones. Even moons and moonlets would’ve been part of the cascade of collisions and impacts.

When nature crams enough objects into a small enough space, it breeds collisions. A new study says that’s what happened at Saturn and created the planet’s dramatic rings.