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MINOR GEOMAGNETIC STORM: A minor G1-class geomagnetic storm is in progress on June 11th as Earth enters a stream of disturbed solar wind. High latitude sky watchers should be alert for auroras, especially in the southern hemisphere where autumn darkness favors visibility. Free: Aurora Alerts
CORONAL MASS EJECTIONS: Despite the lack of sunspots, the sun is active today. SOHO (the Solar and Heliospheric Observatory) has observed two coronal mass ejections (CMEs) on June 11th, a faint one on the sun's western limb and a bright one on the sun's eastern limb: movie. NOAA analysts are working to determine if either of these solar storm clouds will affect Earth in the days ahead. Stay tuned. Free: Aurora Alerts
CRESCENT SUPERMOON VS. FULL MINI-MOON: The Moon's orbit is an ellipse, with one side 50,000 km closer to Earth than the other. This has an effect on the apparent size of the Moon. The lunar disk grows larger when the Moon is nearby and smaller when far away. In the past two weeks we have witnessed two extremes--a crescent supermoon followed by a full 'mini-Moon.' Peter Lowenstein of Mutare, Zimbabwe, photographed them both:
![](images2017/10jun17/moon_strip.jpg)
"The size difference was so great, the crescent Moon of May 27th could hold the full Moon of June 9th with room to spare!" says Lowenstein. "I took these photographs from the same location in Mutare using the same optical zoom setting (x60) on the same Panasonic Lumix DMC TZ-60 camera within two hours of moonset."
Some people say that mini-Moons and supermoons all appear to be the same size. After all, there are no rulers floating in the sky to measure lunar diameters, and without reference points to provide a sense of scale, one Moon can indeed look much like any other. However, Lowenstein's photo shows there is a real difference.
Realtime Space Weather Photo Gallery
SPACE BALLS FOR FATHER'S DAY: What do you give the Father who has everything? Space Balls! The students of
Earth to Sky Calculus have flown a basket of space-helmeted golf balls to the edge of space, 36.3 km (119,000 feet) above Earth's surface on board a high altitude helium balloon:
![](images2016/04jun16/golfballs1_strip.png)
After the balloon exploded, the balls parachuted back to Earth, landing in the volcanic tablelands north of Bishop CA. For $49.95 you can have one of these balls (space helmet included) along with a unique Father's Day card showing the balls floating at the top of Earth's atmosphere. The interior of the card tells the story of the flight and confirms that this gift has been to the edge of space and back again.
More edge of space Father's Day gifts may be found in the Earth to Sky Store.
Far Out Gifts: Earth to Sky Store
All proceeds support hands-on STEM education
DID A SPY SATELLITE JUST VISIT THE ISS? On May 1st at Cape Canaveral, SpaceX launched a classified satellite (USA 276) for the US National Reconnaissance Office. Watching the spysat go into orbit, analysts around the world quickly realized something odd. The orbit of USA 276 was similar to that of the International Space Station and could theoretically make close approaches to the orbiting outpost.
On June 3rd, that's exactly what happened. "USA 276 made a close approach and effectively circled the ISS," reports Marco Langbroek of Leiden, the Netherlands. He prepared this diagram showing the circumstances of the encounter:
![](images2017/07jun17/avoidancebox_strip.png)
Amateur satellite watchers have been tracking USA 276 since late May, and their observations have resulted in ever-improving estimates of the satellite's orbit. "With the latest data included, we can establish the moment of closest approach as 3 June 2017, 14:01:52 UT. It happened in daylight over the southern Atlantic north of the Falklands, near 43o.75 S, 45o.45 W, with a miss distance of only 6.4 ± 2 km."
In the diagram above, the brick-colored box has dimensions of 4 x 4 x 10 km. Whenever an object looks like it is going to pass through that box, ISS mission controllers evaluate the possibility of a collision avoidance maneuver. "USA 276 remained just outside the 4 x 4 x 10 km box at closest approach," notes Langbroek. "As a result, collision avoidance maneuvers were not required."
![](images2017/07jun17/orbit.png)
USA 276 looped around the ISS, according to an analysis by Langbroek
Why is an American spy satellite buzzing the ISS? Maybe it's a chance encounter. Senior satellite analyst Ted Molczan has published arguments for and against that possibility. "I am inclined to believe that the close conjunctions between USA 276 and ISS are intentional," he says.
Molczan points out that USA 276 might be visiting the ISS to test Raven--a technology demonstration project on the ISS researchers are using to develop spacecraft autopilot systems. Raven has visible, infrared, and lidar sensors that can track incoming spacecraft, feeding the data to an onboard processor for decision-making about rendezvous and docking.
"I imagine that USA 276 could add to the Raven data set as follows," speculates Molczan. "If it can rendezvous, then it could keep station for long periods, during which it could change its attitude to present the sensors with a variety of views, under a variety of lighting conditions. The total data collected could potentially far exceed that from the other visiting spacecraft."
If USA 276 does return to the ISS, observers will probably know about it. Langbroek has photographed the spysat in the night sky and it is visible to the unaided eye, like a dim 3rd magnitude star. Interested observers can get local flyby times from Heaven's Above or N2YO.
Realtime Space Weather Photo Gallery
Realtime Aurora Photo Gallery
Realtime Comet Photo Gallery
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 Jun. 11, 2017, the network reported 5 fireballs.
(4 sporadics, 1 Daytime Arietid)
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 June 11, 2017 there were 1803 potentially hazardous asteroids.
![](site_images/spacer.gif) |
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2017 KR27 | 2017-Jun-06 | 7 LD | 12.6 | 72 |
2017 KQ27 | 2017-Jun-06 | 1 LD | 10.7 | 24 |
2017 LE | 2017-Jun-07 | 5.2 LD | 9 | 19 |
2017 HV4 | 2017-Jun-10 | 19.5 LD | 3.9 | 50 |
2017 KF3 | 2017-Jun-11 | 12.9 LD | 11.2 | 40 |
2010 VB1 | 2017-Jun-16 | 10.3 LD | 8.3 | 81 |
471984 | 2017-Jun-18 | 19.1 LD | 7.7 | 102 |
441987 | 2017-Jun-24 | 7.9 LD | 12.7 | 178 |
2017 BS5 | 2017-Jul-23 | 3.2 LD | 5.8 | 54 |
Notes: LD means "Lunar Distance." 1 LD = 384,401 km, the distance between Earth and the Moon. 1 LD also equals 0.00256 AU. MAG is the visual magnitude of the asteroid on the date of closest approach. | Cosmic Rays in the Atmosphere |
Readers, thank you for your patience while we continue to develop this new section of Spaceweather.com. We've been working to streamline our data reduction, allowing us to post results from balloon flights much more rapidly, and we have developed a new data product, shown here:
![](cosmicrays/everything_11sep16_strip.png)
This plot displays radiation measurements not only in the stratosphere, but also at aviation altitudes. Dose rates are expessed as multiples of sea level. For instance, we see that boarding a plane that flies at 25,000 feet exposes passengers to dose rates ~10x higher than sea level. At 40,000 feet, the multiplier is closer to 50x. These measurements are made by our usual cosmic ray payload as it passes through aviation altitudes en route to the stratosphere over California.
What is this all about? Approximately 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 radiation sensors that detect cosmic rays, a surprisingly "down to Earth" form of space weather. Cosmic rays can seed clouds, trigger lightning, and penetrate commercial airplanes. Furthermore, there are studies ( #1, #2, #3, #4) linking cosmic rays with cardiac arrhythmias and sudden cardiac death in the general population. Our latest measurements show that cosmic rays are intensifying, with an increase of more than 13% since 2015:
![](images2017/12may17/radplot_strip.png)
Why are cosmic rays intensifying? The main reason is the sun. Solar storm clouds such as coronal mass ejections (CMEs) sweep aside cosmic rays when they pass by Earth. During Solar Maximum, CMEs are abundant and cosmic rays are held at bay. Now, however, the solar cycle is swinging toward Solar Minimum, allowing cosmic rays to return. Another reason could be the weakening of Earth's magnetic field, which helps protect us from deep-space radiation.
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.
The data points in the graph above correspond to the peak of the Reneger-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 Reneger and Georg Pfotzer discovered the maximum using balloons in the 1930s and it is what we are measuring today.
| The official U.S. government space weather bureau |
| The first place to look for information about sundogs, pillars, rainbows and related phenomena. |
| Researchers call it a "Hubble for the sun." SDO is the most advanced solar observatory ever. |
| 3D views of the sun from NASA's Solar and Terrestrial Relations Observatory |
| Realtime and archival images of the Sun from SOHO. |
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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. |
| from the NOAA Space Environment Center |
| the underlying science of space weather |
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