Spotless Days Current Stretch: 0 days 2025 total: 0 days (0%) 2024 total: 0 days (0%) 2023 total: 0 days (0%) 2022 total: 1 day (<1%) 2021 total: 64 days (18%) 2020 total: 208 days (57%) 2019 total: 281 days (77%) 2018 total: 221 days (61%) 2017 total: 104 days (28%) 2016 total: 32 days (9%) 2015 total: 0 days (0%) 2014 total: 1 day (<1%) 2013 total: 0 days (0%) 2012 total: 0 days (0%) 2011 total: 2 days (<1%) 2010 total: 51 days (14%) 2009 total: 260 days (71%) 2008 total: 268 days (73%) 2007 total: 152 days (42%) 2006 total: 70 days (19%) Updated 17 May 2025
Thermosphere Climate Index today: 23.95x1010W Warm Max: 49.4x1010 W Hot (10/1957) Min: 2.05x1010 W Cold (02/2009) explanation | more data:gfx, txt Updated 16 May 2025
Cosmic RaysSolar Cycle 25 is intensifying, and this is reflected in the number of cosmic rays entering Earth's atmosphere. Neutron counts from the University of Oulu's Sodankyla Geophysical Observatory show that cosmic rays reaching Earth are slowly declining--a result of the yin-yang relationship between the solar cycle and cosmic rays. Oulu Neutron Counts Percentages of the Space Age average: today: -5.7% Low 48-hr change: +1.5% Max: +11.7% Very High (12/2009) Min: -32.1% Very Low (06/1991) explanation |more data Updated 17 May 2025 @ 0700 UT
Planetary K-index Now: Kp= 3.67 quiet 24-hr max: Kp= 6.33 storm explanation | more data
Interplanetary Mag. Field Btotal: 7.27 nT Bz: 2.56 nT north more data: ACE, DSCOVR Updated: Today at 1146 UT
Coronal Holes: 17 May 25
Solar wind flowing from this large southern coronal hole should reach Earth on May 19-20. Credit: NASA/SDO | more data
Polar Stratospheric Clouds Colorful Type II polar stratospheric clouds (PSC) form when the temperature in the stratosphere drops to a staggeringly low -85C. NASA's MERRA-2 climate model predicts when the air up there is cold enough:
On May 16, 2025, the Arctic stratosphere is much too hot for polar stratospheric clouds. | more data.
Noctilucent Clouds The southern season for noctilucent clouds (NLCs) is finished. The first clouds were detected over Antarctica on Nov. 19, 2024, and they vanished again on Feb. 21, 2025. The action will shift to the north pole in late May 2025. Until then, the map will remain blank. Updated: Feb. 21, 2025 An instrument onboard NOAA 21 (OMPS LP) is able to detect NLCs (also known as "polar mesospheric clouds" or PMCs). In the daily map, above, each dot is a detected cloud. As the season progresses, these dots will multiply in number and shift in hue from blue to red as the brightness of the clouds intensifies.
SPACE WEATHER NOAA Forecasts
Updated at: 2025 May 17 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
35 %
35 %
CLASS X
10 %
10 %
Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2025 May 17 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
40 %
40 %
MINOR
25 %
30 %
SEVERE
05 %
10 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
10 %
10 %
MINOR
25 %
25 %
SEVERE
60 %
65 %
Saturday, May. 17, 2025
What's up in space
This is an AI Free Zone: Text created by Large Language Models is spreading across the Internet. It's well-written, but frequently inaccurate. If you find a mistake on Spaceweather.com, rest assured it was made by a real human being.
SURPRISE GEOMAGNETIC STORM... This was not in the forecast. An unexpected G2-class geomagnetic storm occured during the early hours of May 17th, sparked by the glancing blow of a CME. Originally expected to miss Earth, the CME was launched on May 12th by an erupting magnetic filament in the sun's northern hemisphere. The ejecta was wider than models predicted, and some of the debris struck Earth after a 4-day tansit from the sun. CME impact alerts:SMS Text
...AND A CHINESE ROCKET PLUME: During the storm, auroras appeared over more than a dozen US states as far south as New Mexico. There was also something more. A white plume bisected the sky, puzzling observers who at first thought it might be a strange form of STEVE. Mike Lewinski photographed the display from Crestone, Colorado:
"The aurora was rippling low on the northern horizon when suddenly a bright streak of light, reminiscent of a rocket re-entry, appeared high in the sky and flowed down to the horizon," Lewinski says.
This plume was not an aurora, and it was not STEVE. We believe it is related to a rocket launch in China. About an hour before the plume appeared (5:39 UTC), Chinese launch startup Landspace launched the ZhuQue-2E rocket from the Jiuquan Satellite Launch Center (4:12 UTC). It carried 6 satellites to orbit including a synthetic aperture radar and multiple space science spacecraft. The white streak may have been a de-orbit burn, or perhaps a circularization burn for the deploying satellites.
ZhuQue-2E is a new type of rocket powered by liquid oxygen and liquid methane. This "methalox" technology was developed by Landspace, and their ZhuQue-2 series of methane rockets are the first to reach orbit ahead of other companies like Elon Musk's SpaceX. Methalox offers several advantages over traditional rocket fuels like kerosene and hydrogen. Methane is more easily stored, burns cleaner, and can be produced on Mars.
LASER-ETCHED FULL MOON CRYSTAL NIGHT LIGHT: This crystal night light comes from the edge of space, and it is bearing a message: "I Love You to the Moon and Back." On April 23, 2025, the students of Earth to Sky Calculus launched it to the stratosphere onboard a giant helium balloon:
You can have it for $135.99. Made of high-quality K9 crystal, the rectangular mini-monolith contains a 3D laser-etched full Moon floating above the text "I Love You to the Moon and Back." It also comes with an LED base, which allows the crystal to be used as a red, green or blue night light.
The students are selling space crystals to pay the helium bill for their high altitude ballooning program. Each one comes with a greeting card showing the item in flight and telling the story of its journey to the stratosphere and back again.
FIZZY TRI-HYDROGEN AURORAS ON JUPITER: NASA's James Webb Space Telescope (JWST) has discovered a new type of aurora "fizzing and popping" on Jupiter. Unlike auroras on Earth, which come from oxygen and nitrogen, Jupiter's arise from a completely different compound: Ionized trihydrogen (H3+).
Trihydrogen is rare on Earth, but it is one of the most abundant ions in the universe, widespread in interstellar space and also in the cloudtops of gas giant planets like Jupiter. The atomic structure of H3+ causes it to glow with infrared light when it is involved in aurora-producing space storms. That's why the infrared cameras of JWST can detect it.
Trihydrogen auroras have been seen before, especially on Neptune, but these auroras on Jupiter are different. They change faster than than theories predict.
"We expected Jupiter's auroras to fade in and out ponderously," says astronomer Jonathan Nichols (University of Leicester), who led the observing team. "Instead, we observed the whole auroral region fizzing and popping with light, sometimes varying by the second.”
Jupiter's auroras also feature "extinction events." Bright regions in the auroral zone can suddenly go dark in a matter of seconds. This graphic highlights one such event:
"The radiance at this location increased steadily for the several minutes [before it] dropped precipitously, reducing in brightness by around 40%," wrote Nichols and his team.
The auroras' variability may be linked to Jupiter's moon Io. On most worlds, auroras are ignited by the solar wind or a CME strike. On Jupiter, volcanic exhaust from Io can do the same job. Io is by far the most volcanically active body in the solar system with dozens of volcanoes erupting simultaneously. Energetic particles emerging from Io's vents create trihydrogen when they strike Jupiter's atmosphere, impressing upon the auroras any irregularities in the volcanic exhaust.
Every night, a network of NASA all-sky cameras scans the skies above the United States for meteoritic fireballs. Automated software maintained by NASA's Meteoroid Environment Office calculates their orbits, velocity, penetration depth in Earth's atmosphere and many other characteristics. Daily results are presented here on Spaceweather.com.
On May 16, 2025, the network reported 7 fireballs. (6 sporadics, 1 eta Aquarid)
In this diagram of the inner solar system, all of the fireball orbits intersect at a single point--Earth. The orbits are color-coded by velocity, from slow (red) to fast (blue). [Larger image] [movies]
Near Earth Asteroids
Potentially Hazardous Asteroids (PHAs) are space rocks larger than approximately 100m that can come closer to Earth than 0.05 AU. None of the known PHAs is on a collision course with our planet, although astronomers are finding new ones all the time.
On May 17, 2025 there were 2349 potentially hazardous asteroids.
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU.
Cosmic Rays in the Atmosphere
SPACE WEATHER BALLOON DATA: Almost once a week, Spaceweather.com and the students of Earth to Sky Calculus fly space weather balloons to the stratosphere over California. These balloons are equipped with sensors that detect secondary cosmic rays, a form of radiation from space that can penetrate all the way down to Earth's surface. Our monitoring program has been underway without interruption for 10 years, resulting in a unique dataset of in situ atmospheric measurements.
Latest results (Nov. 2024): Atmospheric radiation is sharply decreasing in 2024. Our latest measurements in November registered a 10-year low:
What's going on? Ironically, the radiation drop is caused by increasing solar activity. Solar Cycle 25 has roared to life faster than forecasters expected. The sun's strengthening and increasingly tangled magnetic field repels cosmic rays from deep space. In addition, solar coronal mass ejections (CMEs) sweep aside cosmic rays, causing sharp reductions called "Forbush Decreases." The two effects blend together to bring daily radiation levels down.
.Who cares? Cosmic rays are a surprisingly "down to Earth" form of space weather. They can alter the chemistry of the atmosphere, trigger lightning, and penetrate commercial airplanes. According to a study from the Harvard T.H. Chan school of public health, crews of aircraft have higher rates of cancer than the general population. The researchers listed cosmic rays, irregular sleep habits, and chemical contaminants as leading risk factors. A number of controversial studies (#1, #2, #3, #4) go even further, linking cosmic rays with cardiac arrhythmias and sudden cardiac death.
Technical notes: The radiation sensors onboard our helium balloons detect X-rays and gamma-rays in the energy range 10 keV to 20 MeV. These energies span the range of medical X-ray machines and airport security scanners.
Data points in the graph labeled "Stratospheric Radiation" correspond to the peak of the Regener-Pfotzer maximum, which lies about 67,000 feet above central California. When cosmic rays crash into Earth's atmosphere, they produce a spray of secondary particles that is most intense at the entrance to the stratosphere. Physicists Eric Regener and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
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