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 22 Apr 2025
Thermosphere Climate Index
today: 25.43x1010W Warm
Max: 49.4x1010 W Hot (10/1957)
Min: 2.05x1010 W Cold (02/2009) explanation | more data:gfx, txt
Updated 22 Apr 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: -7.2% Low
48-hr change: +0.8%
Max: +11.7% Very High (12/2009)
Min: -32.1% Very Low (06/1991) explanation |more data
Updated 22 Apr 2025 @ 0700 UT
Planetary K-index
Now: Kp=
2.67 quiet
24-hr max: Kp= 3.67 quiet explanation | more
data
Interplanetary Mag. Field
Btotal: 3.82 nT
Bz: 2.01 nT north more data: ACE, DSCOVR Updated: Today at 1146 UT
Coronal Holes: 22 Apr 25
Earth is inside a stream of solar wind flowing from this large coronal hole. 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 April 21, 2025, the Arctic stratosphere is much too hot for Type II 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 Apr 22 2200 UTC
FLARE
0-24
hr
24-48
hr
CLASS M
40
%
40
%
CLASS X
01
%
01
%
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 Apr 22 2200 UTC
Mid-latitudes
0-24
hr
24-48
hr
ACTIVE
40
%
30
%
MINOR
30
%
15
%
SEVERE
10
%
01
%
High latitudes
0-24
hr
24-48
hr
ACTIVE
05
%
15
%
MINOR
20
%
30
%
SEVERE
75
%
45
%
Tuesday, Apr. 22, 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.
THE SOLAR WIND HAS ARRIVED: A stream of solar wind flowing from a large hole in the sun's atmosphere is buffeting Earth's magnetosphere, setting the stage for possible geomagnetic storms. NOAA forecasters predict a G2-class event on April 22nd. Sky watchers across Canada and northern-tier US states from New York to Washington should be alert for auroras. Aurora alerts:SMS Text.
The solar wind sparked these "tie dye" auroras over Fairbanks, Alaska:
"The twilight skies of spring bring about some of the most beautiful pink and purple colors," says photographer Sacha Layos. "We are nearly out of skies dark enough for aurora. If this was the end of the season, it was a great one!"
SPACEX JUST PUNCHED A HOLE IN THE IONOSPHERE: A Falcon 9 rocket lifted off from Cape Canaveral last night (April 21) on a rideshare mission called "Bandwagon-3." In Puerto Rico, Frankie Lucena watched the rocket fly overhead and, then, punch a hole in the ionosphere:
"There's a red glow inside the broad cone of the exhaust," points out Lucena. "That's the ionospheric hole."
If you use GPS, you have experience with the ionosphere. Radio signals passing through the ionosphere can be bent and distorted, causing errors in GPS navigation when the ionosphere is disturbed. Lucena witnessed a significant disturbance.
Water spraying from the Falcon 9 rocket's engine quenched local ionization by as much as 70%, essentially erasing the ionosphere along the rocket’s path. The resulting "hole" was ~100 km long. For reasons having to do with chemistry, ionospheric holes emit a red glow (630 nm) similar to the aurora borealis.
Once rare, ionospheric holes are increasingly common. Ham radio operators may notice them when shortwave signals fail to skip over the horizon. Newly-formed holes can also cause sudden GPS errors. On the bright side, these effects are temporary; re-ionization occurs as soon as the sun comes up again.
CONSTELLATION CAT CRYSTAL NIGHT LIGHT: It's the most far-out feline night light ever--the Constellation Cat. On March 21, 2025, the students of Earth to Sky Calculus launched it to the stratosphere onboard a giant helium balloon.
You can have it for $129.95. Outlined by stars in the style of an astronomical constellation, the laser-etched cat comes with an LED stand that produces a soothing glow for your bedside table. Also included: A unique greeting card shows the cat in flight and tells the story of its journey to the edge of space.
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 Apr 22, 2025, the network reported 26 fireballs.
(16 Lyrids, 10 sporadics)
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 April 22, 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 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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