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Space Weather for 13-July to 27-July

13-July
SUNSPOT SUNSET: Sunspot 786 is as big as the planet Neptune, which means it's easily seen from Earth.

SPACE SHUTTLE DISCOVERY: Scheduled to launch today at 3:51 ET (20:51 UTC); NASA calls off launch due to faulty fuel tank sensor; {wikinews} in the external tank used to detect fuel exhaustion. According to the agency-run NASA TV, the low-fuel sensor was either malfunctioning or damaged. The launch was already facing the threat of a scrub due to thunderstorms in the area. The sensor is one of four used to trigger the engine cutout after launch. Although only two are required for normal operation, and the Shuttle can be flown with one, NASA elected to maintain full redundancy. Should more of the sensors fail, the engine might burn out due to lack of fuel, a situation that has not been tested. The problem was detected during a simulation of an empty tank. When placed in a mode simulating an empty tank, three of the sensors correctly registered that the tank was empty, while the faulty sensor stayed in the "full" state. NASA is currently unsure whether the problem relates to the sensor, the instrumentation circuits reporting the sensor's state, or the simulation circuits.

14-July
SOLAR ACTIVITY: Solar activity has suddenly increased with a series of strong explosions from sunspot 786, the latest an X1-class flare at 1055 UT on July 14th. Because the sunspot is near the sun's western limb (see below), none of the blasts was Earth directed. Nevertheless, coronal mass ejections hurled into space by these explosions (movies: #1, #2) could deliver glancing blows to Earth's magnetic field as early as tonight and continuing through the weekend, possibly sparking geomagnetic storms. Sky watchers in Canada and northern US states should be alert for auroras.

SOLAR LOOPS: Astronomers are monitoring a remarkably beautiful solar prominence today. It's emerging from sunspot 786 near the sun's western limb. This picture, taken on July 13th by Didier Favre of Los Angeles, CA, shows the prominence with Earth side-by-side for comparison. Croquet anyone?

15-July
AURORA ALERT: People in Canada and northern US states should be alert for auroras tonight. A display is possible when one or two coronal mass ejections (CMEs) en route to Earth arrive, sparking a geomagnetic storm. The incoming CMEs were hurled into space on July 13th and 14th by explosions above sunspot 786.

16-July
SOLAR ERUPTION: An enormous prominence has just erupted from the sun. How big was it? From end to end, it measured almost 50 Earth-diameters. The eruption was spectacular but not Earth-directed. Our planet should experience no effects from the blast. ISS FLYBY: Yes, there really are spaceships up there. On July 14th, Stefan Seip photographed this one, the International Space Station, orbiting over Stuttgart, Germany. The horizontal streak is the ISS, "crossing the summer triangle formed by the stars Vega, Deneb and Altair," says Seip. "The inset shows ISS [as seen through] a 10-inch telescope."

17-July
NO AURORAS: A pair of coronal mass ejections (CMEs) swept past Earth on July 16th, but their impacts were weak; they did not spark a geomagnetic storm. Auroras tonight are unlikely.

18-July
BLANK SUN: The sun is blank today—no sunspots. That means explosions such as solar flares and CMEs are very unlikely this week. CORONAL HOLE: Just because the sun is blank doesn't mean there's no space weather. At this moment, Earth is heading for a solar wind stream flowing from this coronal hole. What's a coronal hole? It is a region above the sun's visible surface where solar magnetic fields fail to hold the sun's atmosphere in place. Hot gas flows out of the hole into space as a stream of solar wind. When this particular stream hits Earth, probably on July 20th or 21st, the impact will shake our planet's magnetic field and possibly spark auroras over Canada and some northern US states.

19-July
BLANK SUN: The sun is blank today—no sunspots. That means explosions such as solar flares and CMEs are very unlikely this week.

20-July
BLANK SUN? The Earth-facing side of the sun is utterly blank today—no sunspots. But what about the other side, the farside of the sun? Using a technique called helioseismic holography, astronomers can see the farside of the sun. Pictured below, a holographic image captured on July 18th reveals at least one sunspot "over there." The sunspot might be the source of a farside explosion on July 17th that hurled a bright coronal mass ejection (CME) over the sun's limb. We'll learn more about this active region on July 25th when the sun's rotation turns it toward Earth. Stay tuned.

SOLAR WIND: A solar wind stream is blowing past Earth and buffeting our planet's magnetic field. Sky watchers in Canada and northern US states should be alert for auroras tonight.

21-July
BLANK SUN? The Earth-facing side of the sun is utterly blank today—no sunspots. But what about the other side, the farside of the sun?

SOLAR WIND: A solar wind stream is blowing past Earth and buffeting our planet's magnetic field. Sky watchers in Canada and northern US states should be alert for auroras tonight.

22-July
QUIET SUN: For the fifth day in a row, the Earth-facing side of the sun is blank—no sunspots. Solar flares and auroras are unlikely this weekend. SOLAR OUTLOOK: The Earth-facing side of the sun may be blank, but the other side, the farside of the sun, is certainly not. Something "over there" exploded yesterday, July 21st at 0400 UT, hurling a bright coronal mass ejection over the sun's limb: movie. Later in the day, another explosion threw more material over the limb. Didier Favre of Los Angeles photographed the second blast. Whatever produced these eruptions will soon turn toward Earth, carried around by the sun's 27-day rotation. This means solar activity could increase next week.

BELT OF VENUS: When the sun sets, the western sky can become absolutely stunning, turning beautiful shades of red and orange. You've seen it happen. But have you ever noticed what happens to the other side of the sky? As the sun sets in the west, Earth's own shadow rises in the east. Sandwiched between Earth's rising shadow (below) and ordinary blue sky (above) is the pink "Belt of Venus." Yesterday, at Elwood Beach near Melbourne, Australia, Russell Cockman snapped this picture of the Belt of Venus beneath the full moon. Air molecules within the Belt scatter light from the setting Sun—hence its pink color.

23-July
SUNSPOT #791: The sun is no longer blank. A tiny sunspot is emerging near the sun's northeastern (uuper-left) limb.

METEOR SHOWER: The annual Perseid meteor shower peaks this year on Friday, August 12th. Joining the Perseids will be the planet Mars for a sky show you won't want to miss. [full story]

24-July
QUIET SUN: Solar activity remains very low. CMEs, solar flares and auroras are unlikely this weekend.

RUNNING MAN: You've heard of the Man in the Moon. Now there's a Man on the Sun—the "running man." Jack Newton of British Columbia photographed him yesterday. The running man is, in fact, a solar prominence, a twisted magnetic filament filled with hot glowing gas. And contrary to appearances, it's not going anywhere. This prominence should remain visible in the same place on the sun's limb for another day or so.

25-July
SOLAR FORECAST: The sun has been remarkably blank and quiet lately. Don't be surprised, though, if solar activity surges later this week. For days, something on the farside of the sun has been exploding and throwing coronal mass ejections (CMEs) over the sun's limb. One of these CMEs is pictured. Whatever's "over there"—probably a big sunspot—might soon turn toward Earth as the sun rotates. Keep an eye on the sun's eastern limb in the days ahead.

26-July
SOLAR BLASTS: No fewer than eight coronal mass ejections (CMEs) have exploded away from the sun since July 22nd: SOHO movie (4.8 MB). This high level of activity is not producing auroras on Earth, however, because none of the CMEs is heading our way. All of the blasts have been on the farside of the sun. Using a technique called helioseismic holography, astronomers can "see" the sun's farside. Recent maps reveal two or more sunspots there. These 'spots could be the source of the blasts. If so, a new batch of CMEs could soon be heading toward Earth. Because the sun spins, sunspots on the farside now will be rotating around to face Earth later this week and next.

SPIDERBOW: On July 24th, standing beneath a sunlit tree in Los Angeles, Gary Palmer looked up and saw something extraordinary: a rainbow-colored spider's web. "There was just a narrow beam of light striking the web," says Palmer. "The brilliant colors shimmered as the web blew back and forth in the gentle breeze. I brought my wife and kids out to see it and they were amazed. How beautiful our wonderful world is!" Rainbow-expert Les Cowley explains: "When covered by early morning dew, spider webs sparkle with the colors of a true rainbow. Gary's colors are different—the spider silk itself produces them. A spider spins silk of long molecules that are stretched and coiled to make it strong but also elastic. These molecules somehow (we don't understand the details) diffract narrow beams of sunlight to make the colors. Look even closer and they split into intricate colored beads."

27-July
SOMETHING'S COMING: A big active sunspot group is lurking just behind the sun's eastern limb. How do we know? It keeps exploding and throwing clouds of hot magnetized gas into space. Andreas Murner of Bavaria, Germany took this snapshot of one such blast on July 27th. Soon, perhaps within 48 hours, this hidden sunspot will reveal itself. The sun's 27-day rotation is slowly turning the sunspot toward Earth. If the 'spot remains active, we can expect Earth-directed explosions as early as this weekend and continuing next week.

Tags: spaceweather, sts-114
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