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SpaceWeather.com -- News and information about meteor showers, solar flares, auroras, and near-Earth asteroids
 
Solar wind
speed: 482.8 km/sec
density: 0.18 protons/cm3
more data: ACE, DSCOVR
Updated: Today at 1146 UT
X-ray Solar Flares
6-hr max: M3
2152 UT Apr21
24-hr: M3
2152 UT Apr21
explanation | more data
Updated: Today at: 2350 UT
Daily Sun: 21 Apr 24
Expand: labels | no labels | Carrington
A southern sunspot complex centered on AR3645 is crackling with M-class solar flares and may be poised to unleash an X-flare. Credit: SDO/HMI

Sunspot number: 240
What is the sunspot number?
Updated 21 Apr 2024

Spotless Days
Current Stretch: 0 days
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 21 Apr 2024


Thermosphere Climate Index
today: 20.21x1010 W Warm
Max: 49.4
x1010 W Hot (10/1957)
Min: 2.05
x1010 W Cold (02/2009)
explanation | more data: gfx, txt
Updated 20 Apr 2024

The Radio Sun
10.7 cm flux: 210 sfu
explanation | more data
Updated 21 Apr 2024

Cosmic Rays Solar 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: -4.3% Low
48-hr change: +0.2%
Max: +11.7% Very High
(12/2009)
Min: -32.1% Very Low (06/1991)
explanation | more data
Updated 21 Apr 2024 @ 0700 UT

Current Auroral Oval:
Switch to: Europe, USA, New Zealand, Antarctica
Credit: NOAA/Ovation
Planetary K-index
Now: Kp= 3.67 quiet
24-hr max: Kp= 4.00
unsettled
explanation | more data
Interplanetary Mag. Field
Btotal: 6.93 nT
Bz: 0.06 nT north
more data: ACE, DSCOVR
Updated: Today at 1147 UT
Coronal Holes: 21 Apr 24

There are no significant equatorial coronal holes on the Earthside of the sun.
Credit: SDO/AIA

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 Apr. 19, 2024, the Arctic stratosphere is much too warm for Type II polar stratospheric clouds. | more data.

Noctilucent Clouds
The southern season for NLCs is over. The first clouds were detected inside the Antarctic Circle on Dec. 4, 2023, by the NOAA 21 satellite. The same satellite detected the last cloud on Feb. 21, 2024. Daily maps are now blank:

noctilucent clouds
Updated: Feb 22, 2024

An instrument onboard NOAA 21 (OMPS LP) is able to detect NLCs (also known as "polar mesospheric clouds" or PMCs). Now that the southern season has ended, attention turns to the northern hemisphere. The first NLCs should appear inside the Arctic Circle in mid to late May.

SPACE WEATHER
NOAA Forecasts
Updated at: 2024 Apr 21 2200 UTC
FLARE
0-24 hr
24-48 hr
CLASS M
75 %
75 %
CLASS X
20 %
20 %
Geomagnetic Storms:
Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm
Updated at: 2024 Apr 21 2200 UTC
Mid-latitudes
0-24 hr
24-48 hr
ACTIVE
25 %
25 %
MINOR
05 %
15 %
SEVERE
01 %
05 %
High latitudes
0-24 hr
24-48 hr
ACTIVE
15 %
15 %
MINOR
25 %
25 %
SEVERE
30 %
45 %
 
Sunday, Apr. 21, 2024
What's up in space
       
 

This is an AI Free Zone! Text created by Large Language Models is spreading rapidly across the Internet. It's well-written, artificial, frequently inaccurate. If you find a mistake on Spaceweather.com, rest assured it was made by a real human being.

 

LYRID METEOR ALERT: The first significant meteor shower in months is about to begin. The annual Lyrid meteor shower peaks on the night of April 21-22 when Earth passes through a stream of debris from Comet Thatcher (C/1861 G1). These meteors are best seen from the northern hemisphere where the radiant is high in the sky before dawn: sky map.

THIS IS THE WORST TIME TO OBSERVE 'THE DEVIL COMET': If you get your science news from mainstream media, you might think this weekend is a great time to observe Comet 12P/Pons-Brooks, a.k.a. "The Devil Comet." In fact, the opposite is true. The comet--barely a naked eye object on the best of nights--is almost completely overwhelmed by a combination of evening twilight and full Moonlight.

To illustrate the problem, Mike Olason photographed the comet sinking into the haze near of Tucson, Arizona, on April 20th:

"As one can see from the animation, the images were collected as twilight started to fade only to be replaced by moonshine from the 87% illuminated Moon," says Olason. "It also did not help that the comet was at an altitude below 6 degrees. Most of the tail and coma were washed out by light pollution, twilight, Moonlight and atmospheric interference."

The kernel of truth in mainstream reports is that Comet 12P is at perihelion on April 21st--its closest approach to the sun. Solar heat is indeed brightening the comet to its maximum luminosity. However, Earth and the comet are far apart on opposite sides of the sun, and we have to squint through the glare of the sun to see the comet.

It all adds up to poor visibility--for now. In May the comet will move away from the sun and into the night skies of the southern hemisphere. In fact, astronomer Michael Mattiazzo is already seeing it from Australia.

Realtime Comet Photo Gallery
Free:
Spaceweather.com Newsletter

YOU'RE GOING TO WANT TO CLICK ON THIS IMAGE: The white-light sun is a blinding ball of featureless light. But... if you filter the light, and look only at the narrow range of wavelengths emitted by hydrogen, the true sun is revealed. This weekend in Kentucky, amateur astronomer Richard Schrantz used a spectroheliograph to do just that, and here is what he saw:

Click on the image for full resolution--and "make sure you look using a large desktop monitor," says Schrantz. "The sunspot complex centered on AR3645 has lots of fine detail."

A spectroheliograph is a special telescope which can photograph the sun at a single narrow wavelength of light--in this case, the "H-alpha" wavelength emitted by solar hydrogen. Schrantz's spectroheliograph image reveals not only a large number of sunspots, but also an even larger number of filaments--magnetic tubes filled with dense hydrogen snaking across the solar disk. These filaments can erupt to produce solar flares and CMEs much like sunspots do; they significantly boost the odds of solar activity. Solar flare alerts: SMS Text

Realtime Space Weather Photo Gallery
Free:
Spaceweather.com Newsletter

18K GOLD TOTAL ECLIPSE PENDANT: This pendant has touched the shadow of the Moon. On April 8, 2024, during a total eclipse of the sun in Texas, the students of Earth to Sky Calculus launched it to the stratosphere onboard a cosmic ray research balloon. Floating more than 118,110 feet high, the locket spent 3 minutes and 45 seconds wrapped in lunar shadow:

You can have it for $199.95. The 18K gold-plated locket is inscribed with the words "I love you to the Moon and back," and opens to hold a personal photo or other small item. It comes with a greeting card showing the locket in flight and telling the story of its journey to the edge of space during the total eclipse.

Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education


Realtime Aurora Photo Gallery
Free:
Spaceweather.com Newsletter


Realtime Comet Photo Gallery
Free:
Spaceweather.com Newsletter


  All Sky Fireball Network
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 21, 2024, the network reported 3 fireballs.
(3 Lyrids)

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 21, 2024 there were 2349 potentially hazardous asteroids.
Recent & Upcoming Earth-asteroid encounters:
Asteroid
Date(UT)
Miss Distance
Velocity (km/s)
Diameter (m)
2024 GK6
2024-Apr-16
8 LD
8.3
15
2024 GN2
2024-Apr-16
1.2 LD
18.5
19
2024 HA
2024-Apr-16
0 LD
19.5
2
2024 GF3
2024-Apr-16
13.9 LD
12.9
25
2024 GS5
2024-Apr-16
1.8 LD
18.3
22
2024 GM1
2024-Apr-17
3.5 LD
10.4
27
2024 HO
2024-Apr-17
0.5 LD
10.2
6
2024 GF5
2024-Apr-17
9.7 LD
7.4
12
2024 FF4
2024-Apr-18
16.1 LD
13
51
2024 GJ6
2024-Apr-18
2.5 LD
8.1
9
2024 GA6
2024-Apr-18
2.7 LD
7.1
12
2023 HU3
2024-Apr-18
15.9 LD
19.1
35
2024 GL5
2024-Apr-18
16.7 LD
11.7
26
2024 FU4
2024-Apr-19
19.2 LD
7.5
29
2024 GP7
2024-Apr-19
7.4 LD
3.6
11
2021 JW2
2024-Apr-19
1.6 LD
5.1
11
2024 HQ
2024-Apr-19
0.8 LD
7.5
5
2017 SA20
2024-Apr-19
3.8 LD
6.2
8
2024 FT4
2024-Apr-19
19.3 LD
5.2
21
2024 HL
2024-Apr-19
4.8 LD
19.7
17
2024 GD5
2024-Apr-20
13.8 LD
4.5
14
2024 GF6
2024-Apr-20
2.3 LD
8.2
15
2024 HR
2024-Apr-20
19.1 LD
17.7
44
2024 HD
2024-Apr-21
5.9 LD
5.6
14
2024 GM
2024-Apr-21
18.7 LD
10.8
89
2024 GW3
2024-Apr-21
19.5 LD
13.3
39
2024 HY
2024-Apr-22
5.7 LD
9.2
76
2024 HS
2024-Apr-23
19.5 LD
5.7
26
2021 VH2
2024-Apr-25
9.3 LD
2.7
6
2024 FG5
2024-Apr-26
12.5 LD
9.1
35
2024 HT
2024-Apr-26
17.3 LD
9.4
30
2024 GR1
2024-Apr-27
19.6 LD
7.2
52
2024 GS4
2024-Apr-28
10.6 LD
12.8
33
2024 GK5
2024-Apr-29
12.9 LD
5.2
39
2021 GD3
2024-Apr-30
11.2 LD
3.5
14
2022 TN1
2024-Apr-30
18.6 LD
17.7
314
2022 AA5
2024-May-02
12 LD
8.9
67
2024 FR5
2024-May-05
4.9 LD
5.2
49
2021 JG9
2024-May-10
16.9 LD
16.1
32
2016 FT14
2024-May-10
19.9 LD
5.9
39
2015 KJ19
2024-May-14
15.8 LD
23.1
112
2014 WF6
2024-May-14
7.2 LD
18.9
47
2021 JN10
2024-May-14
17.5 LD
13.2
33
2021 JJ
2024-May-15
17.2 LD
5.8
28
2022 WN2
2024-May-17
13.7 LD
5.5
6
2019 VB5
2024-May-21
7.8 LD
6.3
2
2024 HP
2024-May-24
15.6 LD
7.6
209
2008 LD
2024-May-28
7.7 LD
4.5
6
2021 LV
2024-May-29
12 LD
15.5
9
1998 KY26
2024-Jun-01
12 LD
5.3
25
2016 JC6
2024-Jun-01
19.9 LD
7.1
188
2008 YN2
2024-Jun-05
10.5 LD
7.7
20
2021 LW3
2024-Jun-06
9.7 LD
9.8
86
2024 CR9
2024-Jun-11
19.2 LD
7.4
447
2022 XC1
2024-Jun-12
16.5 LD
6.5
21
2022 WW11
2024-Jun-17
19.7 LD
14.4
15
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 7 years, resulting in a unique dataset of in situ atmospheric measurements.

Latest results (July 2022): Atmospheric radiation is decreasing in 2022. Our latest measurements in July 2022 registered a 6-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.

  Essential web links
NOAA Space Weather Prediction Center
  The official U.S. government space weather bureau
Atmospheric Optics
  The first place to look for information about sundogs, pillars, rainbows and related phenomena.
Solar Dynamics Observatory
  Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever.
STEREO
  3D views of the sun from NASA's Solar and Terrestrial Relations Observatory
Solar and Heliospheric Observatory
  Realtime and archival images of the Sun from SOHO.
SolarMonitor.org
  information about sunspots based on the latest NOAA/USAF Active Region Summary
Starlink Satellite Statistics
  current counts of failed and deployed Starlink satellites from Jonathan's Space Page. See also, all satellite statistics.
The Aerospace Corporation
  Authoritative predictions of space junk and satellite re-entries
Daily Sunspot Summaries
  from the NOAA Space Environment Center
NOAA 27-Day Space Weather Forecasts
  fun to read, but should be taken with a grain of salt! Forecasts looking ahead more than a few days are often wrong.
Aurora 30 min forecast
  from the NOAA Space Environment Center
Live Aurora Webcam
  from Lights over Lapland
Heliophysics
  the underlying science of space weather

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