This is an AI Free Zone: AI writing is everywhere -- except here. Spaceweather.com is written 100% 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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NEW! STARLINK TRAIN ALERTS: You've probably heard about Starlink's "string of pearls" -- a bright train that forms in the night sky for a few days after the launch of each new batch of satellites. Now you can see one. Our Backyard Astronomy Alert Service now includes Starlink Train Alerts. You'll receive a text and email whenever a string of pearls is about to fly over your backyard. Sign up now.
WHAT IS GOING ON WITH THIS COMET? Last week, astronomers pointed their telescopes at Comet 10P/Tempel 2 for a special event. On July 20th, Earth crossed the comet's orbital plane, and we saw its dust trail edge-on as an exquisitely thin line. Dan Bartlett of June Lake, California, kept watching after the crossing--and he caught something unexpected:
In addition to the razor line of dust everyone else was seeing, Bartlett's deep images picked up a twisting, wave-like structure. It is reminiscent of waves in the narrow rings of Saturn caused by the gravitational shepherding of Saturn's moons.
Yet this comet has no moons. So what's going on? A likelier explanation involves geometry and the subtle difference between a comet's trail and a comet's tail.
The trail of 10P is what everyone was looking for--a pancake of ancient dust. This pancake takes centuries to form. Every time the comet swings around the sun, it leaves behind some heavy grains of dust. Eventually these grains settle into a narrow plane, which looks dramatic when you cross it.
The tail is completely different. This is a plume of fresh dust that emerges when the comet approaches the sun. It spews in its own direction and contains a lot of lightweight grains that get pushed around by sunlight.
A curved tail seen nearly edge-on might read as a ripple in the comet's otherwise flat trail.
Is that what Bartlett saw? There's one way to find out: More observations. Astronomers are encouraged to photograph 10P as we rise out of the comet's orbital plane. A changing point of view might reveal the dynamics and 3D shape of this apparent wave, and thus its true nature. Submit your images here.
Realtime 10P/Tempel Photo Gallery
Free: Spaceweather.com Newsletter
STERLING SILVER SPACE CAT PENDANT:Are you looking for a far-out gift? Consider the Sterling Silver Space Cat. On July 22nd, the students of Earth to Sky Calculus launched it to the stratosphere onboard a cosmic ray research balloon:
You can have it for $139.95. This feline astronaut is made of genuine sterling silver and hangs from a matching 18-inch sterling silver chain. It is a purrfect birthday, anniversary or belated graduation gift.
The students are selling space pendants to pay the helium bill for their cosmic ray ballooning program. Each one comes with a greeting card showing the jewelry in flight and telling the story of its trip to the stratosphere and back again.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
Realtime Aurora Photo Gallery
Free: Spaceweather.com Newsletter
Realtime Space Weather Photo Gallery
Free: Space Weather 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 July 26, 2026, the network reported 40 fireballs.
(39 sporadics, 1 Northern June Aquilids)
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 July 27, 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 OQ1 |
2026-Jul-22 |
2.3 LD |
5.2 |
7 |
| 2026 OU |
2026-Jul-23 |
9.6 LD |
6.3 |
31 |
| 2026 OD1 |
2026-Jul-23 |
17.9 LD |
8 |
48 |
| 2026 KU3 |
2026-Jul-24 |
7.7 LD |
8.6 |
80 |
| 2026 OQ |
2026-Jul-25 |
11.4 LD |
5.7 |
15 |
| 2026 OC3 |
2026-Jul-25 |
2.9 LD |
14.7 |
14 |
| 2026 OD |
2026-Jul-25 |
4.6 LD |
9.5 |
75 |
| 2026 OD3 |
2026-Jul-25 |
0.6 LD |
13 |
10 |
| 2020 UR1 |
2026-Jul-25 |
18.8 LD |
7.6 |
28 |
| 2026 OB1 |
2026-Jul-25 |
2.3 LD |
22.4 |
22 |
| 2015 BF |
2026-Jul-26 |
17.3 LD |
12.5 |
17 |
| 2026 OA3 |
2026-Jul-27 |
4.9 LD |
5.2 |
23 |
| 2026 OL |
2026-Jul-27 |
15.9 LD |
15.9 |
87 |
| 2026 OR |
2026-Jul-28 |
10.4 LD |
10.4 |
16 |
| 2025 OW |
2026-Jul-30 |
16.1 LD |
20.1 |
70 |
| 2026 OS |
2026-Aug-01 |
3.1 LD |
5.8 |
9 |
| 2024 RM10 |
2026-Aug-05 |
13.6 LD |
7.5 |
24 |
| 2026 OE1 |
2026-Aug-07 |
7.6 LD |
10.2 |
50 |
| 173561 |
2026-Aug-09 |
13.1 LD |
16.2 |
756 |
| 2019 NY2 |
2026-Aug-10 |
6.6 LD |
9.6 |
195 |
| 2013 QC11 |
2026-Aug-13 |
14.5 LD |
19 |
172 |
| 2026 NY |
2026-Aug-13 |
12.4 LD |
8.2 |
101 |
| 2025 AL2 |
2026-Aug-16 |
2.2 LD |
12.4 |
100 |
| 2025 DU7 |
2026-Aug-19 |
8.7 LD |
2.9 |
5 |
| 2025 FY11 |
2026-Aug-20 |
19.2 LD |
3.5 |
6 |
| 2023 RL |
2026-Aug-25 |
12.9 LD |
4.8 |
7 |
| 523609 |
2026-Aug-27 |
18.5 LD |
22.7 |
441 |
| 2025 QM9 |
2026-Aug-28 |
15.2 LD |
11.1 |
20 |
| 221455 |
2026-Aug-28 |
9.4 LD |
19 |
443 |
| 2017 BP31 |
2026-Aug-28 |
11.2 LD |
20.5 |
382 |
| 2007 EK |
2026-Aug-30 |
10.9 LD |
9.1 |
5 |
| 2017 RH16 |
2026-Aug-31 |
8.7 LD |
12.1 |
21 |
| 2025 CL3 |
2026-Sep-01 |
9.6 LD |
13.5 |
30 |
| 2018 RD2 |
2026-Sep-01 |
19.5 LD |
9.6 |
14 |
| 2025 QV5 |
2026-Sep-02 |
14.2 LD |
7.3 |
12 |
| 2020 YA5 |
2026-Sep-06 |
19.5 LD |
10.4 |
47 |
| 2022 RK |
2026-Sep-06 |
13.7 LD |
8.6 |
24 |
| 2024 RV12 |
2026-Sep-09 |
5.6 LD |
12.1 |
22 |
| 2026 OH3 |
2026-Sep-11 |
12.4 LD |
20.2 |
198 |
| 2025 RQ2 |
2026-Sep-11 |
17.5 LD |
12.1 |
17 |
| 2010 FX9 |
2026-Sep-14 |
9.4 LD |
11.1 |
55 |
| 2025 SC |
2026-Sep-14 |
19.2 LD |
1.9 |
3 |
| 2024 RP12 |
2026-Sep-16 |
17.9 LD |
6.6 |
51 |
| 2026 NT2 |
2026-Sep-17 |
16.1 LD |
12.5 |
279 |
Notes: LD means
"Lunar Distance." 1 LD = 384,401 km, the distance
between Earth and the Moon. 1 LD also equals 0.00256
AU.
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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 |
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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 |
| |
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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