| | Switch to: Europe, USA, New Zealand, Antarctica Credit: NOAA/Ovation Planetary K-index Now: Kp= 3 quiet 24-hr max: Kp= 5 storm explanation | more data Interplanetary Mag. Field Btotal: 12.6 nT Bz: -12.1 nT south more data: ACE, DSCOVR Updated: Today at 0005 UT Coronal Holes: 19 Apr 17 Solar wind flowing from the indicated coronal hole should reach Earth on April 18-19. Credit: NASA/SDO. Noctilucent Clouds The southern season for noctilucent clouds began on Nov. 17, 2016. Come back to this spot every day to see the "daily daisy" from NASA's AIM spacecraft, which is monitoring the dance of electric-blue around the Antarctic Circle. Switch view: Ross Ice Shelf, Antarctic Peninsula, East Antarctica, Polar Updated at: 02-24-2017 17:55:02 SPACE WEATHER NOAA Forecasts | | Updated at: 2017 Apr 19 2200 UTC FLARE | 0-24 hr | 24-48 hr | CLASS M | 10 % | 10 % | CLASS X | 01 % | 01 % | Geomagnetic Storms: Probabilities for significant disturbances in Earth's magnetic field are given for three activity levels: active, minor storm, severe storm Updated at: 2017 Apr 19 2200 UTC Mid-latitudes | 0-24 hr | 24-48 hr | ACTIVE | 40 % | 25 % | MINOR | 15 % | 10 % | SEVERE | 01 % | 01 % | High latitudes | 0-24 hr | 24-48 hr | ACTIVE | 10 % | 15 % | MINOR | 25 % | 25 % | SEVERE | 50 % | 35 % | | | | | | | | | | | | Looking for a far-out Mother's Day gift? Find something truly out of this world in the Earth to Sky Store. Space roses, Cosmic Reindeer, Arctic space pendants, and more! | | | ASTEROID FLYBY TODAY: Approaching from the direction of the sun, mountain-sized asteroid 2014 JO25 is flying past Earth today, April 19th, approximately 1.8 million km away. NASA says there is no danger of a collision, but it is close enough for amateur astronomers to photograph in backyard telescopes. It looks like a fast-moving speck of light (magnitude +11) zipping among the stars. Canadian astrophotographer Mario Hebert used a 10-inch telescope at the Parc national de la Mauricie in Quebec to capture this movie of 2014 JO25 nearing Earth on April 18th. Got an image? Submit it here. SPECTACULAR CME: Old sunspot AR2644 has returned--and it is still active. On April 18th at approximately 2000 UT, the sunspot's magnetic canopy exploded and hurled a bright coronal mass ejection (CME) into space. The ESA/NASA Solar and Heliophysics Observatory caught the cloud as it raced away from the sun:
This CME will probably miss Earth. The explosion's epicenter was too far off the Sun-Earth line for a direct hit. NOAA analysts are still evaluating the possibility of a glancing blow, however, so stay tuned for updates. More CMEs may be in the offing. In early April this sunspot produced a series of strong M-class flares and shortwave radio blackouts on Earth. Geoeffective activity stopped only when the sunspot went into hiding on the farside of the sun. Two weeks later it's back, and it is turning toward Earth for a new round of solar activity. Note: By longstanding tradition, sunspots that travel around the backside of the sun and re-appear are renumbered. AR2644 therefore has a new designation: AR2651. We will use both names in our coverage of this active region in the days ahead. Realtime Aurora Photo Gallery SCINTILLATING SIRIUS: Sirius is the brightest star in the sky. It is also, arguably, the most colorful. On any given evening of northern Spring, sky watchers can behold a spray of rainbow colors emanating from the Dog Star as it sets low in the southwestern sky. Tom Wagner of Waterloo, Iowa, has developed a beautiful way to display the star's hue. "Decades ago I discovered that by wiggling my binoculars while looking at Sirius, I could easily see the colors of the rainbow flash by in rapid succession." On April 16th he took this picture through the eyepiece: "This is a 2 second exposure," he says. "The colors were spectacular!" Astronomers call this phenomenon "scintillation." Also known as "twinkling," the phenomenon is caused by thermal irregularities in Earth's atmosphere. As packets of relatively warm and cool air drift in front of a star, the star's light is refracted. The prismatic action of these air packets produce rainbow colors--especially near the horizon where starlight must pass through many turbulent irregularities to reach the observer. All stars scintillate, but Sirius does so most flamboyantly because of its extreme brightness. See for yourself. Step outside this evening after sunset and look southwest for Sirius near the feet or Orion. The lower it gets, the more it twinkles. Enjoy the show! Realtime Space Weather 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 Apr. 19, 2017, the network reported 10 fireballs. (10 sporadics) 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 19, 2017 there were 1798 potentially hazardous asteroids. | Recent & Upcoming Earth-asteroid encounters: Asteroid | Date(UT) | Miss Distance | Velocity (km/s) | Diameter (m) | 2017 GO4 | 2017-Apr-15 | 13.8 LD | 6 | 34 | 2014 UR | 2017-Apr-19 | 18.8 LD | 4.4 | 17 | 2014 JO25 | 2017-Apr-19 | 4.6 LD | 33.6 | 852 | 2017 GL4 | 2017-Apr-20 | 17.5 LD | 7.4 | 22 | 2017 GM4 | 2017-Apr-20 | 13.1 LD | 16.6 | 143 | 2017 FH101 | 2017-Apr-24 | 18.8 LD | 9.9 | 103 | 2017 FE157 | 2017-Apr-29 | 18.6 LD | 8.6 | 64 | 2015 VD1 | 2017-May-07 | 18.2 LD | 10.5 | 34 | 2012 EC | 2017-May-16 | 19.5 LD | 4.5 | 74 | 2017 CS | 2017-May-29 | 8 LD | 9.1 | 468 | 418094 | 2017-Jun-01 | 8 LD | 23.2 | 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 12% 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." 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