Terry's Astronomy Thread.

[Bluearrowll]

What's in the sky tonight?
September 22, 2013

-The September equinox occurs at 4:44 p.m. EDT today, when the Sun crosses the equator heading south for the season. Fall begins in the Northern Hemisphere, spring in the Southern Hemisphere.

-As summer ends, the Sagittarius Teapot moves to the west of south during evening and tips increasingly far over, as if pouring out summer's last drops.

-NASA's Solar Dynamics Observatory is monitoring a coronal hole in the sun's northern hemisphere. It is the UV-dark region in this image taken during the early hours of Sept. 21st. The white lines in the image trace the sun's magnetic field. A coronal hole is a place where the magnetic field spreads apart, allowing solar wind to escape. A stream of solar wind flowing from this particular coronal hole is heading for Earth, due to arrive on Sept. 23-24. Its arrival could add to the impact of a minor CME expected to reach Earth at about the same time. Polar geomagnetic storms are possible early next week.

Astro Picture of the Day:
September 22, 2013

Source:
Today, the Sun crosses the celestial equator heading south at 20:44 Universal Time. An equinox (equal night), this astronomical event marks the first day of autumn in the northern hemisphere and spring in the south. With the Sun on the celestial equator, Earth dwellers will experience nearly 12 hours of daylight and 12 hours of darkness. To celebrate, consider this remarkable record of the Sun's yearly journey through planet Earth's sky, made with planned multiple exposures captured on a single piece of 35 millimeter film. Exposures were made at the same time of day (9:00am local time), capturing the Sun's position on dates from January 7 through December 20, 2003. The multiple suns trace an intersecting curve known as an analemma. A foreground base exposure of the Temple of Apollo in ancient Corinth, Greece, appropriate for an analemma, was digitally merged with the film image. Equinox dates correspond to the middle points (not the intersection point) of the analemma. The curve is oriented at the corresponding direction and altitude for the temple, so the Sun's position for the September equinox is at the upper midpoint near picture center. Summer and winter solstices are at analemma top and bottom.