APOD: Zodiacal Light Over Namibia (2010 Sep 13)

[APOD Robot]

Zodiacal Light Over Namibia

Explanation: An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually zodiacal light, light reflected from interplanetary dust particles. The bright reflecting triangle is clearly visible on the right of the above horizontally-compressed image taken just after sunset from Namibia in the southern hemisphere in 2009 June. The central band of our Milky Way Galaxy on the left first mirrors the zodiacal band on the right but then curves around the sky. The faint smudges inside the arch of the Milky Way are the Large and Small Magellanic Clouds Zodiacal dust orbits the Sun predominantly in the same plane as the planets: the ecliptic. Zodiacal light is so bright in the north this time of year because the dust band is oriented nearly vertical at sunrise, so that the thick air near the horizon does not block out relatively bright reflecting dust. Zodiacal light is also bright for people in Earth's northern hemisphere in March and April just after sunset. In the southern hemisphere, zodiacal light is most notable after sunset in late summer, and brightest before sunrise in late spring.

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[neufer]

Zodiacal Light Over Namibia

The reason the camera is pointing to the south west:

<<The [Namibian] Capella-Observatory [before moving to Mount Skinakas, Crete] is located about 20km southwest of Windhoek (Namibia) at the Kupferberg (Cooperhill), about 2100 m above sea level. The nearness to Windhoek results in a light polluted sky to the North East direction, but to the South direction the sky is as black as a hole. First experiences show, that the seeing, which is so important for astronomical images, is moderate (2.5" FWHM) to good (1.5" FWHM). Until now, we have no experiences with the seeing in the "cold season" (May-August), but we hope to have even better values.>>
--------------------------------------------
<<After its move from Namibia [to Crete] the Capella Observatory is located about 25 km south west to Heraklion/Crete (Greece), nearly 1750 m above sea on top of Mount Skinakas. The nearness to Heraklion results in an illuminated sky in north east direction, but all other directions show no or nearly no light pollution. Some kilometers away in direction Psiloritis (the highest mountain on Crete, 2456 m) the Idäic Grotto, the legendary place, at which Zeus (Jupiter) was lactated by the goat Amalthea and where he hid from his father Chronos (Saturn) is located. Because of heavy thunderstorms, freezing rain and snow the observatory is closed regulary from middle of November until end of March. During these months it is only accessible on foot.>>

[orin stepanek]

Zodiacal light in the eastern sky before the beginning of morning twilightZodiacal light is a faint, roughly triangular, whitish glow seen in the night sky which appears to extend up from the vicinity of the sun along the ecliptic or zodiac. Caused by sunlight scattered by space dust in the zodiacal cloud, it is so faint that either moonlight or light pollution renders it invisible. The zodiacal light decreases in intensity with distance from the Sun, but on very dark nights it has been observed in a band completely around the ecliptic. In fact, the zodiacal light covers the entire sky, being responsible for 60% of the total skylight on a moonless night. There is also a very faint, but still slightly increased, oval glow directly opposite the Sun which is known as the gegenschein.

This phenomenon was first investigated by the astronomer Giovanni Domenico Cassini in 1683 and first explained by Nicolas Fatio de Duillier in 1684.

I've noticed glow in the sky at night at times; but was never curious as to what it was.

[neufer]

Zodiacal Light Over Namibia

Explanation: An unusual triangle of light is visible this time of year just before dawn, in the northern hemisphere. Once considered a false dawn, this triangle of light is actually zodiacal light, light reflected from interplanetary dust particles. The bright reflecting triangle is clearly visible on the right of the above horizontally-compressed image taken just after sunset from Namibia in the southern hemisphere in 2009 June. The central band of our Milky Way Galaxy on the left first mirrors the zodiacal band on the right but then curves around the sky. The faint smudges inside the arch of the Milky Way are the Large and Small Magellanic Clouds Zodiacal dust orbits the Sun predominantly in the same plane as the planets: the ecliptic. Zodiacal light is so bright in the north this time of year because the dust band is oriented nearly vertical at sunrise, so that the thick air near the horizon does not block out relatively bright reflecting dust. Zodiacal light is also bright for people in Earth's northern hemisphere in March and April just after sunset. In the southern hemisphere, zodiacal light is most notable after sunset in late summer, and brightest before sunrise in late spring.

This gets my vote for the most convoluted APOD explanation of all time!

I've noticed glow in the sky at night at times; but was never curious as to what it was.

My guess is that it's either Windhoek or Heraklion.

(Do you live in the southern hemisphere or the northern hemisphere, Orin?)

[bystander]

(Do you live in the southern hemisphere or the northern hemisphere, Orin?)

orin stepanek
Resident Geezer

Posts: 1880
Joined: 2005/07/27 10:41:07
Location: Nebraska

[neufer]

(Do you live in the southern hemisphere or the northern hemisphere, Orin?)

orin stepanek
Resident Geezer

Posts: 1880
Joined: 2005/07/27 10:41:07
Location: Nebraska

My condolences.

[brother sally]

Today’s APOD shows the three most distinctive great circles. In addition to the galactic plane and the ecliptic, by looking carefully at the bends of the star trails, you can see the celestial equator.

[Butcher]

This might be an impressive example of a sky phenomena in a technical sense, but I gotta say it's a pretty ugly APOD.

[Athanasius]

Is anyone else annoyed by the change lately to having the mouse-over image (for annotations) be based on a slightly different image ? In this case it is an entirely different image (dome closed/open, light off/on on a structure to the left...).

I really just want to flick between no-annotations and annotations, not also minutely retrack to whatever part of the image I was looking at.