Tag Archives: Sun

Sun online and solar activity 26.11.2014


INFO FROM SIDC – RWC BELGIUM 2014 Nov 26 12:25:23 Four C-class flare were observed, with NOAA 2217 producing the strongest event of the period (C2.9 peaking at 06:17UT). Slowly developing region NOAA 2219 and a new, currently unnumbered, region near the east limb merit some attention, as they were the sources of the other C-class flares. Numerous, but quiet, filaments are present on the solar disk, with the longest measuring 40 degrees and located in the NE quadrant. No Earth-directed CMEs were observed. Further C-class flaring is expected, with a small chance on an isolated M-class flare. Solar wind speed declined from about 400 to 320 km/s. Bz was mostly negative and varied between -6 and +4 nT. The IMF is directed away from the Sun. The geomagnetic field was quiet to unsettled (K<4), and is expected to remain so. Effects from an expected Sector Boundary Crossing and the possible high speed stream from the extension of a coronal hole may result in an isolated active period on 27-28 November.

The Sun online and solar activity. 14.10.2014

солнце 14 октября



No C flares occurred during the past 24 hours. In the next 48 hours, Cflares are possible, especially from beta regions NOAA AR 2187 and2188.Over the last 24 hours, solar wind speed observed by ACE hasfluctuated between about 340 and 430 km/s. The magnitude of theInterplanetary Magnetic Field (IMF) first varied between 3 and 9 nT, andincreased further to 13 nT from around 4h UT on October 14.Over the past 24 hours, geomagnetic conditions were quiet (K Dourbesbetween 1 and 3; NOAA Kp between 1 and 3). Quiet geomagnetic levels (KDourbes < 4) are expected on October 14, 15 and 16, with a chance foractive levels (K Dourbes = 4).

Mercury’s Transit: An Unusual Spot on the Sun 

Image Credit & Copyright: David Cortner

 What’s that dot on the Sun? If you look closely, it is almost perfectly round. The dot is the result of an unusual type of solar eclipse that occurred in 2006. Usually it is the Earth’s Moon that eclipses the Sun. This time, the planet Mercury took a turn. Like the approach to New Moon before a solar eclipse, the phase of Mercury became a continually thinner crescent as the planet progressed toward an alignment with the Sun. Eventually the phase of Mercury dropped to zero and the dark spot of Mercury crossed our parent star. The situation could technically be labeled a Mercurian annular eclipse with an extraordinarily large ring of fire. From above the cratered planes of the night side of Mercury, the Earth appeared in its fullest phase. Hours later, as Mercury continued in its orbit, a slight crescent phase appeared again. The next Mercurian solar eclipse will occur in 2016.

APOD NASA 24-Aug-14

A Solar Filament Erupts 

Magnificent CME Erupts on the Sun - August 31

Image Credit: NASA’s GSFC, SDO AIA Team

 What’s happened to our Sun? Nothing very unusual — it just threw a filament. Toward the middle of 2012, a long standing solar filament suddenly erupted into space producing an energetic Coronal Mass Ejection (CME). The filament had been held up for days by the Sun’s ever changing magnetic field and the timing of the eruption was unexpected. Watched closely by the Sun-orbiting Solar Dynamics Observatory, the resulting explosion shot electrons and ions into the Solar System, some of which arrived at Earth three days later and impacted Earth’s magnetosphere, causing visible aurorae. Loops of plasma surrounding an active regioncan be seen above the erupting filament in the ultraviolet image. Over the past week the number of sunspots visible on the Sun unexpectedly dropped to zero, causing speculation that the Sun has now passed a very unusualsolar maximum, the time in the Sun’s 11-year cycle when it is most active.

APOD NASA 20-Jul-14

Spotty Sunrise over Brisbane 

Image Credit & Copyright: Stephen Mudge

In this composite cityscape, dawn’s first colors backdrop the lights along Brisbane’s skyline at the southeastern corner of Queensland, Australia, planet Earth. Using a solar filter, additional exposures made every 3.5 minutes follow the winter sunrise on July 8 as planet-sized sunspots cross the visible solar disk. The sunspots mark solar active regions with convoluted magnetic fields. Even as the maximum in the solar activity cycle begins to fade, the active regions produce intense solar flares and eruptions launching coronal mass ejections (CMEs), enormous clouds of energetic particles, into our fair solar system.

APOD NASA 11-Jul-14

A Green Flash from the Sun

Image Credit & Copyright: Daniel López (El Cielo de Canarias)

Many think it is just a myth. Others think it is true but its cause isn’t known. Adventurers pride themselves on having seen it. It’s a green flash from the Sun. The truth is the green flash does exist and its cause is well understood. Just as the setting Sun disappears completely from view, a last glimmer appears startlingly green. The effect is typically visible only from locations with a low, distant horizon, and lasts just a few seconds. Agreen flash is also visible for a rising Sun, but takes better timing to spot. A dramatic green flash, as well as an even more rare red flash, was caught in the above photograph recently observed during a sunset visible from the Observatorio del Roque de Los Muchachos in the Canary Islands, Spain. The Sun itself does not turn partly green or red — the effect is caused by layers of the Earth’s atmosphere acting like a prism.
NASA APOD 04-Jun-14

Orange Sun Sparking 


Image Credit & Copyright: Alan Friedman (Averted Imagination)

Our Sun has become quite a busy place. Taken only two weeks ago, the Sun was captured sporting numerous tumultuous regions including active sunspot regions AR 2036 near the image top and AR 2036near the center. Only four years ago the Sun was emerging from an unusually quiet Solar Minimum that had lasted for years. The above image was recorded in a single color of light called Hydrogen Alpha, inverted, and false colored. Spicules cover much of the Sun’s face like a carpet. The gradual brightening towards the Sun’s edges is caused by increased absorption of relatively cool solar gas and called limb darkening. Just over the Sun’s edges, several filamentary prominences protrude, while prominences on the Sun’s face are seen as light streaks. Possibly the most visually interesting of all are the magnetically tangled active regions containing relatively cool sunspots, seen as white dots. Currently at Solar Maximum — the most active phase in its 11-year magnetic cycle, the Sun’s twisted magnetic field is creating numerous solar “sparks” which include eruptive solar prominences, coronal mass ejections, and flares which emit clouds of particles that may impact the Earth and cause auroras. One flare two years ago released such a torrent of charged particles into the Solar System that it might have disrupted satellites and compromised power grids had it struck planet Earth.

NASA APOD 06-May-14

Solargraphy Analemmas

Image Credit & Copyright: Maciej Zapiór and Łukasz Fajfrowski

Today is the equinox. The Sun crosses the celestial equator heading north at 16:57 UT, marking the northern hemisphere’s first day of spring. To celebrate, consider this remarkable image following the Sun’s yearly trek through planet Earth’s sky, the first analemmas exposed every day through the technique of solargraphy. In fact, three analemma curves were captured using a cylindrical pinhole camera by daily making three, separate, one minute long exposures for a year, from March 1, 2013 to March 1, 2014, on a single piece of black and white photographic paper. The well-planned daily exposures began at 10:30, 12:00, and 13:30, CET from a balcony looking south from the Kozanów district in Wrocław, Poland. That year’s two equinoxes on March 20 and September 22 correspond to the mid-points, not the cross-over points, along the figure-8 shaped curves. Apparent gaps in the curves are due to cloudy days. Two solid lines at the lower left were both caused by a timer switch failure that left the pinhole shutter open.

NASA APOD 20-mar-2014

Equinox on a Spinning Earth


Image Credit: NASA, Meteosat, Robert Simmon

When does the line between day and night become vertical? Tomorrow. Tomorrow is an equinox on planet Earth, a time of year when day and night are most nearly equal. At an equinox, the Earth’s terminator — the dividing line between day and night — becomes vertical and connects the north and south poles. The above time-lapse video demonstrates this by displaying an entire year on planet Earth in twelve seconds. From geosynchronous orbit, the Meteosat satellite recorded these infrared images of the Earth every day at the same local time. The video started at the September 2010 equinox with the terminator line being vertical. As the Earth revolved around the Sun, the terminator was seen to tilt in a way that provides less daily sunlight to the northern hemisphere, causing winter in the north. As the year progressed, the March 2011 equinox arrived halfway through the video, followed by the terminator tilting the other way, causing winter in the southern hemisphere — and summer in the north. The captured year ends again with the September equinox, concluding another of billions of trips the Earth has taken — and will take — around the Sun.

NASA APOD 19-mar-14

The Sun Rotating

Video Credit: SDO, NASA; Digital Composition: Kevin Gill (Apoapsys)
Does the Sun change as it rotates? Yes, and the changes can vary from subtle to dramatic. In the above time-lapse sequences, our Sun – as imaged by NASA’s Solar Dynamics Observatory – is shown rotating though the entire month of January. In the large image on the left, the solar chromosphere is depicted in ultraviolet light, while the smaller and lighter image to its upper right simultaneously shows the more familiar solar photosphere in visible light. The rest of the inset six Sun images highlight X-ray emission by relatively rare iron atoms located at different heights of the corona, all false-colored to accentuate differences. The Sun takes just under a month to rotate completely – rotating fastest at the equator. A large and active sunspot region rotates into view soon after the video starts. Subtle effects include changes in surface texture and the shapes of active regions. Dramatic effects include numerous flashes in active regions, and fluttering and erupting prominences visible all around the Sun’s edge. This year our Sun is near its Solar maximum activity of its 11-year magnetic cycle. As the video ends, the same large and active sunspot region previously mentioned rotates back into view, this time looking differently.

NASA APOD 12-mar-2014