INFORMATION

NASA’s Apollo program most notably explored the Moon. But it also helped us study the Earth as well, as it provided some of the first high-resolution images of our whole planet, like the famous “Blue Marble” photo taken by the Apollo 17 astronauts. However, these full-Earth photos revealed a mystery.  Scientists expected that Earth’s two hemispheres, the north and south, would have different albedos, a difference in the amount of light they reflect. This is because Earth’s northern and southern hemispheres of Earth are quite different from each other. The southern hemisphere is mostly covered with dark oceans, while the northern hemisphere contains vast land areas that are much brighter than the oceans Yet, when observing Earth from space, the two hemispheres appear equally bright. This symmetry in brightness has been a puzzle for over 50 years. But now, a new study shows that the albedos are roughly the same because of the increased clouds and storms in the southern hemisphere...

When NASA crashed a 610 kg (1,340 lb) impactor into tiny Dimorphos, a moon of the asteroid Didymos, it was all part of an effort to defend Earth. The impact showed how asteroids respond to impacts, and the data is helping NASA prepare for the day when we have to redirect an asteroid away from an eventual impact with Earth. NASA’s DART (Double Asteroid Redirection Test) smashed into Dimorphos on the 26th of September, 2022, and ground telescopes watched the result. DART was a success. The impact lowered Dimorphos’ orbital speed and reduced its orbital radius. DART also changed Didymos’ trajectory and excavated a crater on the Dimorphos’ surface that ejected more than 900,000 kg (990 US tons) of debris into space. The Hubble Space Telescope got in on the action and captured images several hours apart until about 18 days after the impact. There’s a little bit of mystery in the debris. At first, debris moves away from the impact in straight lines. It’s travelling at about 6.5...

Stars are born in molecular clouds, massive clouds of hydrogen that can contain millions of stellar masses of material. But how do molecular clouds form? There are different theories and models of that process, but the cloud formation is difficult to observe. A new study is making some headway, and showing how the process occurs more rapidly than thought. Molecular clouds are an important part of the interstellar medium (ISM) and are embedded in atomic gas, the other main component of the ISM. The third component of the ISM is ionic gas, and all three play roles in star formation. There are unanswered questions about how molecular hydrogen clouds form from the ISM and then form stars. Molecular hydrogen is notoriously difficult to observe because of its lack of absorption lines in visible, infrared, and UV light. New research shows how one component of the ionized gas in the ISM—ionized carbon (CII)—can be observed to trace how molecular clouds form. The new research appears in N...

Dust storms are a serious hazard on Mars. While smaller storms and dust devils happen regularly, larger ones happen every year (during summer in the southern hemisphere) and can cover continent-sized areas for weeks. Once every three Martian years (about five and a half Earth years), the storms can become large enough to encompass the entire planet and last up to two months. These storms play a major role in the dynamic processes that shape the surface of Mars and are sometimes visible from Earth (like the 2018 storm that ended the Opportunity rover’s mission). When Martian storms become particularly strong, the friction between dust grains causes them to become electrified, transferring positive and negative charges through static electricity. According to research led by planetary scientist Alian Wang at Washington University in St. Louis, this electrical force could be the major driving force of the Martian chlorine cycle. Based on their analysis, Wang and her colleagues believe ...

Sending a lander to Venus presents several huge engineering problems. Granted, we’d get a break from the nail-biting entry, descent and landing, since Venus’ atmosphere is so thick, a lander would settle gently to the surface like a stone settles in water — no sky cranes or retrorockets required. But the rest of the endeavor is fraught with challenges. The average temperature at the surface is 455 degrees C (850 F), hot enough to melt lead. The mix of chemicals that make up the atmosphere, such as sulfuric acid, is corrosive to most metals. And the crushing atmospheric pressure is roughly equivalent to being 1,500 meters (5,000 ft) under water. These extreme environmental conditions are where metals and electronics go to die; therefore, the few Venus lander missions that have made it to the surface — like the Soviet Venera missions — only lasted two hours or less. Any future landers or rovers will need to have nearly super-hero-type characteristics to endure on the surface of Earth’s...

An asteroid the size of the Empire State Building flew past Earth in early February, coming within 1.8 million km (1.1 million miles) of our planet. Not only is it approximately the same size as the building, but astronomers found the asteroid – named 2011 AG5 — has an unusual shape, with about the same dimensions as the famous landmark in New York City. “Of the 1,040 near-Earth objects observed by planetary radar to date, this is one of the most elongated we’ve seen,” said Lance Benner, principal scientist at JPL who helped lead the observations, in a JPL press release. This extremely elongated asteroid has a length-to-width ratio of 10:3. The orbit of asteroid 2011 AG5 carries it beyond the orbit of Mars and as close to the sun as halfway between Earth and Venus. Image credit: NASA/JPL/Caltech/NEOPO Since there was no risk of this asteroid hitting our planet, astronomers took the opportunity to study 2011 AG5, as this is the closest pass the asteroid has made to Earth since i ...

Jupiter is well known for its spectacular aurorae , thanks in no small part to the Jun o orbiter and recent images taken by the James Webb Space Telescope (JWST). Like Earth, these dazzling displays result from charged solar particles interacting with Jupiter’s magnetic field and atmosphere. Over the years, astronomers have also detected faint aurorae in the atmospheres of Jupiter’s largest moons (aka. the “ Galilean Moons “). These are also the result of interaction, in this case, between Jupiter’s magnetic field and particles emanating from the moons’ atmospheres. Detecting these faint aurorae has always been a challenge because of sunlight reflected from the moons’ surfaces completely washes out their light signatures. In a series of recent papers , a team led by the University of Boston and Caltech (with support from NASA) observed the Galilean Moons as they passed into Jupiter’s shadow. These observations revealed that Io, Europa, Ganymede, and Callisto all experience oxygen-...