DAYTIME METEOR SHOWER: The annual Arietid meteor shower peaks tomorrow, June 5th. It's a strong shower, but the meteors are difficult to see because the sun is up when the shower is most intense. The Arietids are a rare daytime meteor shower. Sky watchers who want to see an Arietid are encouraged to look east during the dark hour just before dawn on Monday. Earth-grazing Arietids are long, bright and beautiful. [more]
THE THERMOSPHERE IS HEATING UP: If you're a satellite, this story is important. A series of geomagnetic storms in 2023 has pumped terawatts of energy into Earth's upper atmosphere, helping to push its temperature and height to a 20-year high. Air surrounding our planet is now touching satellites in Earth orbit and dragging them down.
"Blame the sun," says Martin Mlynczak of NASA Langley. "Increasing solar activity is heating the top of the atmosphere. The extra heat has no effect on weather or climate at Earth's surface, but it's a big deal for satellites in low Earth orbit."
Above: A severe geomagnetic storm on March 24, 2023, photographed by Michael Underwood from Yellowstone National Park
Mlynczak is an expert on the temperature up there. For 20 years he has been using the SABER instrument on NASA's TIMED satellite to monitor infrared emissions from "the thermosphere," the uppermost layer of the atmosphere.
"Right now we’re seeing some of the highest readings in the mission's 21.5 year history," he says.
The thermosphere is exquisitely sensitive to solar activity, readily absorbing energy from solar flares and geomagnetic storms. These storms have been coming hard and fast with the recent rise of Solar Cycle 25.
"There have been five significant geomagnetic storms in calendar year 2023 that resulted in marked increases in the amount of infrared radiation (heat) in Earth's thermosphere," says Mlynczak. "They peaked on Jan. 15th (0.59 TW), Feb. 16th (0.62 TW), Feb. 27th (0.78 TW), Mar. 24th (1.04 TW), and April 24th (1.02 TW)."
The parenthetical values are TeraWatts (1,000,000,000,000 Watts) of infrared power observed by SABER during each storm. The sensor obtains these numbers by measuring infrared radiation emitted from nitric oxide and carbon dioxide molecules in the thermosphere.
Above: NASA's daily Thermosphere Climate Index tracks thermal energy in Earth's upper atmosphere. So far, Solar Cycle 25 is far ahead of Solar Cycle 24. Credit: Linda Hunt
"The two storms exceeding 1 TW are the seventh and eighth strongest storms observed by SABER over the past 21.5 years," he says. "It is interesting to note that each successive storm in 2023 is generally stronger than its predecessors."
Actually, it doesn't take a strong storm to cause problems. In Feb. 2022, a minor geomagnetic storm dumped enough heat into the thermosphere that 38 newly launched Starlink satellites fell out of the sky. SpaceX has since started launching their Starlinks to higher initial altitudes to avoid the drag.
If current trends continue, the thermosphere will warm even more in 2023 and 2024. This is a matter of concern because Earth's population of active satellites has tripled since SpaceX started launching Starlinks in 2019. The growing constellation of 4100 Starlinks now provides internet service to more than a million customers. An extreme geomagnetic storm like the Halloween Storms of 2003 could shift the positions of these satellites by many 10s of kilometers, increasing the risk of collisions and causing some of the lowest ones to de-orbit.
Stay tuned as the warming continues.
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SOLAR ECLIPSE CRYSTAL PYRAMID: On Aug. 21, 2017, during the Great American Solar Eclipse, the students of Earth to Sky Calculus launched 11 space weather balloons from the path of totality. The armada soared into the stratosphere, touching the shadow of the Moon more than 100,000 feet above Earth's surface. This pyramid hitched a ride:
You can have it for $159.95. With the sun, Earth, and Moon perfectly aligned, the faces of the 5-sided crystal caught the reflection of the eclipsed sun. Watch the video! The pyramid comes with a gift card showing the crystal floating at the top of Earth's atmosphere and passing through the Moon's shadow. The interior of the card tells the story of the flight and confirms that this gift has been to the edge of space and back again.
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