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SUNSET PLANETS: When the sun goes down tonight, step outside and look west. An exquisitely slender crescent Moon is passing by Mercury in the rosy glow of sunset. Tomorrow night is even better when the Moon passes by Venus. Enjoy the show. Sky maps: July 14, 15.
GREEN FLASH ON THE SUN: For seaside photographers, nothing beats a green flash--that sudden pulse of verdant light at sunset as the sun vanishes beneath the ocean waves. James Young was on a beach in Oregon on July 11th when captured a green flash. But it didn't come from the ocean waves. It came from the top of a cloud:
This is a rare 'cloud-top' green flash, sometimes seen as the sun's rays graze a distant cloud bank. They are not well understood. Ordinary green flashes require a temperature inversion layer near the sea surface. Similar inversions may sometimes occur at the top of marine stratus clouds, giving rise to the type of ragged green flash Young witnessed.
"It was very bright--a beautiful mystery to end the day," he says.
Realtime Green Flash Photo Gallery
GREEN FLASH ON MARS: Mars is approaching Earth for a 15-year close encounter on July 27th. The Red Planet now outshines every object in the sky except the sun, Moon, and Venus. Mars is doing things only very luminous objects can do--like produce a green flash. Watch this video taken by Peter Rosén of Stockholm, Sweden, on July 12th:
"Mars was shining brightly in the early morning sky," he says. "At an altitude of only 6.5° above the horizon, the turbulence was extreme, sometimes splitting the planet's disc in 2 or 3 slices and displaying a green and blue flash resembling those usually seen on the sun."
That's not all. Mars is also making its own glitter paths. Last night, Alan Dyer photographed this specimen from Driftwood Beach at Waterton Lakes National Park, Alberta:
A glitter path is a band of light in the water. It is caused by reflections from the troughs and crest of tiny waves. Normally, only the sun and Moon (and sometimes Venus and Jupiter) produce glitter paths. Now Mars is doing it too.
Dyer notes that Mars was "bright yellow"--a hue caused in part by the massive global dust storm in progress there. Think about it: A dust storm on another planet that you can see with your naked eye. Mars is close.
Still two weeks before closest approach, Mars is almost 3 times brighter than Sirius, the brightest star in the sky, and 30% brighter than the giant planet Jupiter. In other words, you can't miss it. Look south at midnight and remember, the best is yet to come. [sky map]
Realtime Space Weather Photo Gallery
FLY ME TO THE MOONSTONE: Are you looking for a far-out gift? Nothing says "I love you" like a moonstone from the edge of space. On June 12th, the students of Earth to Sky Calculus flew this moonstone wrapped in a sterling silver Celtic love knot 34.1 km (111,877 feet) above Earth's surface:
You can have it for $119.95. The students are selling these pendants to support their cosmic ray ballooning program. Each one comes with a greeting card showing the item in flight and telling the story of its journey to the edge of space. Sales support the Earth to Sky Calculus cosmic ray ballooning program and hands-on STEM research.
Far Out Gifts: Earth to Sky Store
All sales support hands-on STEM education
Realtime Noctilucent Cloud Photo Gallery
Realtime Aurora 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 Jul. 14, 2018, the network reported 16 fireballs.
(15 sporadics, 1 psi Cassiopeid)
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 14, 2018 there were 1912 potentially hazardous asteroids.
|
Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) |
2018 NQ3 | 2018-Jul-10 | 14.6 LD | 8.9 | 20 |
2018 NF1 | 2018-Jul-12 | 18.1 LD | 10.8 | 38 |
2018 NW1 | 2018-Jul-14 | 9.9 LD | 9.2 | 28 |
2018 NV2 | 2018-Jul-15 | 10.1 LD | 15.1 | 43 |
2018 NM | 2018-Jul-17 | 1.4 LD | 6.7 | 19 |
2018 NQ1 | 2018-Jul-19 | 16.4 LD | 6 | 32 |
2018 NE1 | 2018-Jul-21 | 10.1 LD | 14.2 | 83 |
2018 NR1 | 2018-Jul-27 | 17.1 LD | 5.1 | 37 |
2018 LQ2 | 2018-Aug-27 | 9.4 LD | 1.5 | 39 |
2016 GK135 | 2018-Aug-28 | 16.8 LD | 2.8 | 9 |
2016 NF23 | 2018-Aug-29 | 13.3 LD | 9 | 93 |
1998 SD9 | 2018-Aug-29 | 4.2 LD | 10.7 | 51 |
2018 DE1 | 2018-Aug-30 | 15.2 LD | 6.5 | 28 |
2001 RQ17 | 2018-Sep-02 | 19.3 LD | 8.3 | 107 |
2015 FP118 | 2018-Sep-03 | 12.3 LD | 9.8 | 490 |
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:
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:
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. |
| from the NOAA Space Environment Center |
| 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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