This is an AI Free Zone: AI is everywhere -- except here. Spaceweather.com is written by Dr. Tony Phillips, a carbon-based lifeform with 30 yrs of forecasting experience. If you find a mistake, rest assured it was made by a real human being.
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THE LYRID METEOR SHOWER PEAKS TONIGHT: The annual Lyrid meteor shower peaks tonight, April 21-22, when Earth passes through a stream of debris from Comet Thatcher (C/1861 G1). This shower typically produces about 15 naked-eye meteors per hour. A fun way to experience the Lyrids is listening to their radio reflections. Tune in here.
'TIS THE SEASON FOR RARE BLUE AURORAS: Blue auroras are very rare. Even veteran aurora chasers with years of Arctic experience have seldom seen them. Yet there is a time of year when they become easier to find--and that time is now.
"Last night, a blue aurora appeared overhead," reports Geir T. Birkeland Øye of Ørsta, Norway. "This is a sight we don't often see."
Auroras are almost always red or green--colors produced by oxygen during solar storms. Blue, on the other hand, is a sign of nitrogen. The color is produced by solar wind particles hitting ionized nitrogen molecules (N2+) at the top of Earth's atmosphere. The problem is, there are very few N2+ ions up there. The feeble blue they emit is practically invisible.
For blue auroras to reach naked-eye visibility, something must amplify the light. The amplification process is called "resonant scattering," and it was definitely happening on April 21st.
Look at the glowing horizon in Øye's photo--that is the key. The sun was barely below the horizon, perfectly postioned to illuminate the "nitrogen zone." Nitrogen ions floating 200-300 km above the ground absorbed and re-emitted sunlight, amplifying a faint blue (427.8 nm) emission into a visible, brilliant blue glow.
"At this time of year, astronomical darkness does not occur here; the sun remains higher than about -13°," explains Øye. "This creates a seasonal window where the upper atmosphere remains sunlit while the ground-level sky is still dark enough for auroras to be visible. That combination is ideal for enhancing N2+ emissions through resonant scattering."
Arctic sky watchers: 'Tis the season for blue auroras. If you see them, submit your photos here.
Realtime Aurora Photo Gallery
Free: Spaceweather.com Newsletter
"DIAMOND RING" SUN HALO: Yesterday in Nattages, France, photographer Christian Viladrich looked up and did a double take. "I saw this strange solar halo offset from the sun," he says. It looked like a diamond ring:
The ring of light passing through the sun is a "full parhelic circle." It is among the rarest of ice halos. Full parhelic circles require as many as five internal reflections from millions of individual ice crystals, all catching sunbeams simultaneously.
For such a display to occur, the sky must fill with a rare mixture of gem-like ice crystals in wispy cirrus clouds. Viladrich looked up at just the right moment!
Realtime Space Weather Photo Gallery
Free: Spaceweather.com Newsletter
"ALWAYS AND FOREVER" SPACE PENDANT: Are you looking for a far out gift? Consider the 'Always and Forever' Space Pendent. The students of Earth to Sky Calculus launched it to the top of Earth's atmosphere onboard a cosmic ray research balloon:
It's yours for $279.95. Engraved with the words "I love you always and forever," this sterling silver pendant features a heart-shaped citrine crystal surrounded by a ring of glittering 5A cubic zirconia nuggets. It comes with a greeting card showing the jewelry in flight and telling the story of its journey to space.
The students of Earth to Sky Calculus are selling space pendants to support their high-altitude balloon program. Each pendant has flown above 99.7% of Earth's atmosphere, experiencing space-like blasts of cosmic rays, extreme cold, and a wild ride parachuting back to Earth after the balloon explodes. All sales support student science projects and STEM education.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
Realtime Comet Photo Gallery
Free: Spaceweather.com Newsletter
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 April 19, 2026, the network reported 1 fireball.
(1 sporadic)
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]
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 21, 2026 there were 2349 potentially hazardous asteroids.
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Recent
& Upcoming Earth-asteroid encounters:
| Asteroid |
Date(UT) |
Miss Distance |
Velocity (km/s) |
Diameter (m) |
| 2026 HE1 |
2026-Apr-16 |
4.1 LD |
5.1 |
8 |
| 2026 HB1 |
2026-Apr-16 |
12.1 LD |
6.1 |
13 |
| 2026 HX1 |
2026-Apr-16 |
0.3 LD |
12.4 |
6 |
| 2026 GP2 |
2026-Apr-16 |
8.4 LD |
18.2 |
21 |
| 2026 HY |
2026-Apr-16 |
3.5 LD |
12.4 |
11 |
| 2026 GT |
2026-Apr-16 |
11.7 LD |
16 |
18 |
| 2026 GA2 |
2026-Apr-16 |
3.6 LD |
10.5 |
14 |
| 2026 GT2 |
2026-Apr-16 |
5.7 LD |
28.7 |
31 |
| 2026 GQ2 |
2026-Apr-16 |
1 LD |
6.9 |
5 |
| 2026 HE |
2026-Apr-17 |
11 LD |
6.8 |
20 |
| 2026 GA1 |
2026-Apr-17 |
12.2 LD |
7.8 |
21 |
| 2026 HP |
2026-Apr-17 |
3.5 LD |
7.4 |
14 |
| 2026 HG |
2026-Apr-17 |
2.8 LD |
8 |
6 |
| 2026 HJ2 |
2026-Apr-17 |
2.5 LD |
18.3 |
31 |
| 2026 GO2 |
2026-Apr-17 |
17.8 LD |
20.5 |
49 |
| 2026 GR2 |
2026-Apr-18 |
7.7 LD |
6.5 |
12 |
| 2026 FJ6 |
2026-Apr-18 |
15.8 LD |
9.8 |
89 |
| 2026 HC2 |
2026-Apr-18 |
14.4 LD |
15.4 |
26 |
| 2026 HQ |
2026-Apr-18 |
0.4 LD |
3.7 |
2 |
| 2026 HT1 |
2026-Apr-18 |
2.6 LD |
16 |
16 |
| 2026 GM1 |
2026-Apr-18 |
3.5 LD |
5.6 |
29 |
| 2026 HP1 |
2026-Apr-18 |
15.3 LD |
12.3 |
20 |
| 2026 HK1 |
2026-Apr-19 |
0.8 LD |
12 |
4 |
| 2026 HD1 |
2026-Apr-19 |
12.1 LD |
18.4 |
25 |
| 2026 HN |
2026-Apr-19 |
1.6 LD |
11.4 |
16 |
| 2026 HH1 |
2026-Apr-19 |
1.8 LD |
19.2 |
9 |
| 2026 HF1 |
2026-Apr-19 |
14 LD |
13.9 |
23 |
| 2026 HJ |
2026-Apr-19 |
0.3 LD |
6.5 |
3 |
| 2026 HF |
2026-Apr-20 |
9.8 LD |
5.5 |
33 |
| 2026 HG1 |
2026-Apr-20 |
3.3 LD |
6 |
12 |
| 2026 AC4 |
2026-Apr-20 |
10.7 LD |
1.2 |
22 |
| 2022 UG2 |
2026-Apr-20 |
16.3 LD |
10.3 |
13 |
| 2026 HJ1 |
2026-Apr-21 |
1.7 LD |
10.6 |
7 |
| 2026 HF2 |
2026-Apr-21 |
0.3 LD |
18.1 |
10 |
| 2026 GJ1 |
2026-Apr-21 |
8.7 LD |
22.2 |
67 |
| 2025 HQ4 |
2026-Apr-21 |
16.4 LD |
12.5 |
22 |
| 2026 GZ1 |
2026-Apr-21 |
15.5 LD |
10.2 |
50 |
| 2026 GL2 |
2026-Apr-22 |
7.1 LD |
10.4 |
32 |
| 2026 HY1 |
2026-Apr-22 |
3.9 LD |
9.3 |
22 |
| 2026 BK2 |
2026-Apr-22 |
10 LD |
8.1 |
219 |
| 2026 HK |
2026-Apr-22 |
10.8 LD |
18.7 |
26 |
| 2026 HZ1 |
2026-Apr-24 |
14 LD |
7.1 |
18 |
| 2022 UU8 |
2026-Apr-25 |
8.7 LD |
4 |
9 |
| 2026 HR |
2026-Apr-27 |
16.6 LD |
7.6 |
21 |
| 2026 GU1 |
2026-Apr-28 |
12.5 LD |
6.4 |
75 |
| 2026 HW |
2026-Apr-28 |
9.6 LD |
11.8 |
35 |
| 2026 GW3 |
2026-May-02 |
13.8 LD |
5.8 |
22 |
| 2026 HE2 |
2026-May-03 |
15.5 LD |
6.6 |
24 |
| 2026 GD1 |
2026-May-03 |
14.6 LD |
6.6 |
51 |
| 2026 HN1 |
2026-May-06 |
9.2 LD |
14.2 |
67 |
| 2026 HD2 |
2026-May-08 |
17.7 LD |
10.7 |
41 |
| 2020 GE3 |
2026-May-09 |
11.1 LD |
6 |
21 |
| 2023 VR5 |
2026-May-16 |
7.5 LD |
2.3 |
10 |
| 2025 KR4 |
2026-May-18 |
15.2 LD |
5.9 |
22 |
| 2023 KH4 |
2026-May-24 |
5.5 LD |
7.9 |
14 |
| 2023 KZ1 |
2026-May-24 |
9 LD |
13.4 |
20 |
| 2023 BM4 |
2026-May-30 |
12.2 LD |
5.7 |
64 |
| 2021 KN2 |
2026-Jun-03 |
8.9 LD |
8.9 |
7 |
| 2018 GE |
2026-Jun-07 |
16.4 LD |
3.1 |
11 |
| 2016 VS |
2026-Jun-12 |
20 LD |
11.1 |
12 |
| 530520 |
2026-Jun-12 |
16.1 LD |
14.6 |
152 |
| 2003 LN6 |
2026-Jun-18 |
3.7 LD |
3.9 |
41 |
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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The
official U.S. government space weather bureau |
| |
The
first place to look for information about sundogs,
pillars, rainbows and related phenomena. |
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Researchers
call it a "Hubble for the sun." SDO
is the most advanced solar observatory ever. |
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3D
views of the sun from NASA's Solar and Terrestrial
Relations Observatory |
| |
Realtime
and archival images of the Sun from SOHO. |
| |
information about sunspots based on the latest NOAA/USAF Active Region Summary |
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current counts of failed and deployed Starlink satellites from Jonathan's Space Page. See also, all satellite statistics. |
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Authoritative predictions of space junk and satellite re-entries |
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from
the NOAA Space Environment Center |
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fun to read, but should be taken with a grain of salt! Forecasts looking ahead more than a few days are often wrong. |
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from the NOAA Space Environment Center |
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the
underlying science of space weather |
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Got a chipped or cracked windshield that prevents you from seeing space weather events while driving? Get windshield replacement from SR Windows & Glass with free mobile auto glass service anywhere in the Phoenix area. |
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