The Sentinel-6 series
While scientists can track tropical storms for weeks, a storm can quickly turn into a hurricane, leaving little time for updates and things like evacuations if they are necessary.
NASA and its European partners have been tracking weather on Earth for decades using satellites that are in space.
The Sentinel-6 series is a collection of satellites that study things like hurricanes, ocean patterns and things like La Niña and El Niño. Right now, we are in El Niño, the warm phase.
Josh Willis, a climate scientist at NASA’s Jet Propulsion Laboratory said these satellites have been measuring sea level for over 35 years.
“They look down through the clouds and through the atmosphere,” Willis said. “They bounce a radar wave off the surface of the ocean. They time how long it takes to come back, and then if you know that, then you can figure out the distance between the satellite and the ocean. Couple that with information about where the satellite is in space, and we have a measurement of the height of the ocean. So literally, the sea level.”
Right now, the two satellites, Sentinel-6 Michael Freilich and Sentinel-6B, are studying El Niño. According to the National Oceanic and Atmospheric Administration, “an El Niño condition occurs when surface water in the equatorial Pacific becomes warmer than average and east winds blow weaker than normal. The opposite condition is called La Niña. During this phase of ENSO, the water is cooler than normal, and the east winds are stronger.”
Willis said that the satellites study El Niño by looking at the tilting in the ocean water. He said on the west coast of the U.S., they’re seeing an extra foot of sea level.
“The height of the ocean, that sounds kind of strange, right?” Willis said. “There are waves, there's tides, there's all this stuff going on, but the height of the ocean actually tells us where the heat is in the ocean. Because whenever the water is warm, it expands and it literally stands taller.”
Willis said when it comes to hurricanes, the storms are driven by the heat in the ocean. A hurricane’s strength is not just dependent on the water at the surface, but the water below the surface too.
If the water is warm over a big chunk of depth, then as the hurricane comes along, it's not mixing up water that's cooling it off, it's mixing up water that is just as hot as the surface,” Willis said. “So, this tends to put a storm on steroids. Altimeters, or these sea level satellites, show us where those blobs of hot water are underneath the surface. So, they've done a really amazing job at improving our ability to predict how strong a storm is going to be.”
Studying X-ray tails
The Chandra X-ray observatory is the most powerful X-ray telescope in the world. From its home in space, Chandra helps scientists observe things like galaxies, exploded stars, and even things like black holes.
Recently, scientists took a closer look at a new class of objects that Chandra found. Those objects are hypersoft X-ray sources, or low energy X-rays, that come from astronomical objects.
Jimmy Irwin, a professor of physics and astronomy, said by studying X-rays, the observatory studies a higher energy of light that the Hubble Space Telescope or the James Werbb space telescope cannot.
“We’re talking X-rays, sort of like the kind of X-rays you might get at your dental office, although not quite as high-energy, but they'd still fall within the X-ray regime,” Irwin said. “Mainly Chandra is looking for objects that are typically at very high temperature or have some sort of energetic processes that would be able to generate this higher-energy light called X-rays.”
University of Alabama Tuscaloosa’s Mustafa Muhibullah, a doctoral candidate, said the X-ray detections Chandra made aren’t typically seen in our own galaxy because hydrogen and helium absorb that light from what’s called extreme UV emitters.
“We actually detected the faint X-ray tails of these extreme UV emitters,” Muhibullah said. “You can imagine this way, like let's say you have a room filled of light. Now you're outside of that room, and so outside of the room you don't know whether there is a light inside of the room or not. But underneath the door, some light can leak, and that leaked light is actually the faint X-ray tails we are detecting. You can imagine the room's filled light is actually the extreme UV.”
Rosanne Di Stefano, a senior astrophysicist at the Smithsonian Astrophysical Observatory and a lecturer of astronomy at Harvard University said these findings are an extension of what we already know about some of these X-ray sources.
“It means that the class of soft sources has an even softer subclass than people studied before, and that's this new class of hypersoft X-ray sources,” Di Stefana said. “What it means is that black holes, neutron stars, white dwarfs, they're emitting lots of radiation, very high luminosities. But with really large photospheres, the photosphere is the place from which most of the light we detect comes like the Sun has a photosphere that's about, 5,800 Kelvin. So, we don't understand why exactly these large photospheres are there, and it provides us a lot of fuel for additional research.”
