Space News & Blog Articles

NASA’s Perseverance rover mission provided a blueish pre-sunrise gift above Jezero Crater on March 18, 2022, aka Sol 738, or the 738th Martian day of the mission, with “sol” being the official timekeeping method for Mars missions since one Martian day is approximately 40 minutes longer than one Earth day. The car-sized explorer used one of its navigation cameras (Navcam) to snap images of high-altitude clouds drifting in the Martian sky, which it shared on its officially Twitter page on March 23, 2023.

“This is the time of maximum cloud development in the equatorial and mid-latitudes of Mars, between the northern spring equinox and the summer solstice,” Dr. Agustín Sánchez-Lavega, a Professor of Applied Physics at the Bilbao School of Engineering (University of the Basque Country/Euskal Herriko Unibertsitatea UPV/EHU), recently told Universe Today. “Most of the Martian clouds are formed by ice crystals with sizes between 1 and 4 microns and usually form up to 40 km high. These morning clouds observed by Perseverance are of this nature. In addition, carbon dioxide clouds can also form, which are rarer and require very low temperature conditions. The formation and dissipation cycles of these clouds are important as tracers of the amount of water in the atmosphere and of the dynamical processes that take place in it.”

Scientists involved in Mars missions from both NASA and the European Space Agency have a long history of studying Martian cloud formations, even though the Red Planet is primarily known for its dust storms. Images of Martian clouds go as far back as NASA’s Viking Orbiter 1, when it imaged water ice clouds in the Valles Marineris region on August 17, 1976 during local Mars morning time. NASA’s Mars Pathfinder lander also snapped numerous images of Martian clouds throughout its mission in 1996, which lasted 83 sols, or 85 Earth days. Later Mars missions such as NASA’s Curiosity rover also imaged Martian clouds in 2021, as well.

Morning clouds on Mars imaged by NASA’s Viking Orbiter 1 on August 17, 1976. (Credit: NASA/JPL)

Composite image of Martian clouds taken by NASA’s Curiosity rover on March 19, 2021, or Sol 3063, just after sunset. This image is a combination of 21 single images and color correction was used to show how it would look to a human eye. (Credit: NASA/JPL-Caltech/Malin Space Science Systems)

It probably comes as no surprise to people living in low-lying coastal regions, but sea waters are rising by large, measurable amounts. That assessment comes from NASA, which has analyzed 30 years of sea-level satellite measurements. The news is not good. Since 1993, the seas rose by a total of 9.1 centimeters. Two years ago, it went up by 0.27 centimeters.

That one-year rise from 2021 to 2022 may sound small by comparison, but it’s a harbinger. And, it adds up over time. Even taking into account slight shifts due to natural influences like La Niña (which periodically cools the oceans), sea heights continue to rise. Based on continued long-term satellite measurements, the projected rate of sea level rise will hit 0.66 centimeters per year by 2050.

To bring that idea home, last year NASA estimated that levels along the U.S. coastlines could rise as much as 30 centimeters above where they are today by 2050. It could get worse in other parts of the world.

We’re Causing This Sea Level Rise

The culprit for all this is human-caused climate change. It’s driven by the excess amounts of greenhouse gases like carbon dioxide humans pump into the atmosphere. Climate change has a number of effects across the globe, but it’s particularly obvious in Earth’s ice sheets and glaciers. Just this past year alone, the Antarctic ice sheet has experienced above-average melting, even accounting for summer temperatures.

The stability of Greenland’s ice pack has changed a great deal, and today the Greenland Ice Sheet is a major contributor to sea level rise. That’s because its runoff and water from the Antarctic ice add more fresh water to the ocean while warming causes the expansion of seawater. The result is rising seas which override other natural effects on sea surface height.

In 1997, George Lucas released the special edition remaster of his Star Wars trilogy, making changes to the special effects that both delighted and divided fans worldwide (did Han shoot first?). Among the myriad additions was a visually spectacular ring-shaped shockwave emanating from the exploding Death Star, and Alderaan too. Star Trek fans will delightedly point out that this particular special effect had previously been used in the 1991 film Star Trek VI: The Undiscovered Country, in which the Klingon moon Praxis explodes, giving the effect its name: the Praxis ring. Hollywood lore suggests Lucas was so impressed with the effect in that film that he added it to Star Wars too.

Praxis rings look cool on the silver screen, but we all know explosions in space are supposed to be spherical. With no preference for up, down, left, or right, the material blown off an exploding star should push outward in all directions.

Except when it doesn’t. A paper published at the end of March described the flattest explosion ever observed, with a disc of material ejecting out from the core along one plane, just like the Praxis effect.

The explosion is AT2018cow, nicknamed ‘The Cow’ because of the letters in its procedurally generated designation. The Cow is a Fast Blue Optical Transient (FBOT), a rare class of explosion of which only five have ever been seen. FBOTs tend to be in the blue end of the spectra range, and they happen quickly on astronomical time scales: The Cow exhausted most of its energy in 16 days. But FBOTs are also incredibly bright – brighter than most supernovas.

Justyn Maund, the lead author of the paper, said in a press release that “very little is known about FBOT explosions – they just don’t behave like exploding stars should, they are too bright and they evolve too quickly. Put simply, they are weird, and this new observation makes them even weirder.”