Daily Archives: September 14, 2013

Solar eclipses

As seen from the Earth, a solar eclipse occurs when the Moon passes between the Sun and Earth, and the Moon fully or partially blocks (“occults”) the Sun. This can happen only at new moon, when the Sun and the Moon are in conjunction as seen from Earth in an alignment referred to as syzygy. In a total eclipse, the disk of the Sun is fully obscured by the Moon. In partial and annular eclipses only part of the Sun is obscured.
An eclipse is a natural phenomenon. Nevertheless, in some ancient and modern cultures, solar eclipses have been attributed to supernatural causes or regarded as bad omens. A total solar eclipse can be frightening to people who are unaware of its astronomical explanation, as the Sun seems to disappear during the day and the sky darkens in a matter of minutes.

There are four types of solar eclipses:

  • total eclipse occurs when the dark silhouette of the Moon completely obscures the intensely bright light of the Sun, allowing the much fainter solar corona to be visible. During any one eclipse, totality occurs at best only in a narrow track on the surface of Earth.
  • An annular eclipse occurs when the Sun and Moon are exactly in line, but the apparent size of the Moon is smaller than that of the Sun. Hence the Sun appears as a very bright ring, or annulus, surrounding the dark disk of the Moon.
  • hybrid eclipse (also called annular/total eclipse) shifts between a total and annular eclipse. At certain points on the surface of Earth it appears as a total eclipse, whereas at other points it appears as annular. Hybrid eclipses are comparatively rare.
  • partial eclipse occurs when the Sun and Moon are not exactly in line and the Moon only partially obscures the Sun. This phenomenon can usually be seen from a large part of Earth outside of the track of an annular or total eclipse. However, some eclipses can only be seen as a partial eclipse, because the umbra passes above the Earth’s polar regions and never intersects Earth’s surface.

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The Sun Online and solar activity. September 14, 2013

Solar activity is very low, no C-class flares in past 8 days. Geomagnetic conditions were quiet to unsettled in Dourbes, while there was one period of active conditions at planetary levels (Kp=4) from 15:00 UT to 18:00 UT on September 13, due to the influence of the coronal hole related fast solar wind. The Earth is still under the influence of this fast stream, but quiet to unsettled conditions are expected for the next 48h.
INFO from Royal Observatory of Belgium

Local time:9/14/2013 at 7:36:36 Local time:9/14/2013 at 7:36:36 Local time:9/14/2013 at 7:36:36 Local time:9/14/2013 at 7:36:36

Equipment: Coronado 90 + SBIG 8300s + LX75
Editor: Photoshop
Date: 14/09/13
Time GMT: 11:30:00
Exposure 0.09 sec.

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A Landing on Planet Earth

Expedition 36 Soyuz TMA-08M Landing

Image Credit:
NASA, Bill Ingalls

Explanation: With parachute deployed and retro-rockets blazing, this spacecraft landed on planet Earth on September 11 (UT) in a remote area near the town of Zhezkazgan, Kazakhstan. Seen in silhouette against the rockets’ glare, the spacecraft is a Soyuz TMA-08M. Its crew, Expedition 36 Commander Pavel Vinogradov and Flight Engineer Alexander Misurkin of the Russian Federal Space Agency (Roscosmos), and Flight Engineer Chris Cassidy of NASA were returning after five and half months aboard the International Space Station. The Soyuz retro-rockets fire very quickly and for an extremely short duration near touchdown. Capturing the moment, the well-timed photograph was taken from a helicopter flying over the landing site.