Starship Asterisk*

Ann wrote:Nice green aurora. It's a shade of green which isn't yet yellow-green, but is clearly approaching yellow-green. This is what I think of as the color of 560 nm, bearing in mind that 580 nm is brilliantly yellow. Okay, so maybe this aurora is 555 nm, then!

Anyway, it is a suitable colored aurora over a landmass called Greenland. The dominant color of Greenland is white from snow and ice (even though the ice appears to be melting here - a victim of climate change?), but there are plenty of aurorae to be seen from there!

As for the Big Dipper, it can be seen sitting inside the topmost part of the green arc of the aurora. Please note the Alpha Persei cluster away from the aurora at top right. This cluster is very obvious. And to the left of the bright Moon you can see the moonlight-polluted Pleaides!

Ann

Atomic oxygen is responsible for the two main colors of green (wavelength of 557.7 nm) and red (630.0 nm).

Emily Windsor-Cragg wrote:What's this HUNK of photoshop job in the middle of the photo? Makes is unacceptable as an Album addition.

That while, textured bird-shaped thingie is not part of the photo; somebody was trying to hide something under it.

What a shame.

kaigun wrote:
The ice is melting because it's the middle of August. It happens every year. Speaking of which, this seems like a strange time of the year to do research on the auroras. I guess the location is more hospitable in the summer but at the high latitudes there is still a lot of daylight.

http://en.wikipedia.org/wiki/Aurora_%28astronomy%29 wrote:

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<<Geomagnetic storms that ignite auroras actually happen more often during the months around the equinoxes. The auroras that resulted from the "great geomagnetic storm" on both 28 August and 2 September 1859 are thought the most spectacular in recent recorded history.

Within the auroral zone the likelihood of an aurora occurring depends mostly on the slant of interplanetary magnetic field (IMF) lines (the slant is known as B_z), being greater with southward slants. During spring and autumn, the interplanetary magnetic field and that of Earth link up. At the magnetopause, Earth's magnetic field points north. When B_z becomes large and negative (i.e., the IMF tilts south), it can partially cancel Earth's magnetic field at the point of contact. South-pointing B_z's open a door through which energy from the solar wind can reach Earth's inner magnetosphere. The peaking of B_z during this time is a result of geometry. The IMF comes from the Sun and is carried outward with the solar wind. The rotation of the Sun causes the IMF to have a spiral shape. The southward (and northward) excursions of B_z are greatest during April and October, when Earth's magnetic dipole axis is most closely aligned with the Parker spiral.

However, B_z is not the only influence on geomagnetic activity. The Sun's rotation axis is tilted 8 degrees with respect to the plane of Earth's orbit. The solar wind blows more rapidly from the Sun's poles than from its equator, thus the average speed of particles buffeting Earth's magnetosphere waxes and wanes every six months. The solar wind speed is greatest – by about 50 km/s, on average – around 5 September and 5 March when Earth lies at its highest heliographic latitude.

Still, neither B_z nor the solar wind can fully explain the seasonal behavior of geomagnetic storms. Those factors together contribute only about one-third of the observed semiannual variations.>>

Malcolm wrote:M34 in Perseus, top middle right, is visible just above and to the right of Algol.
Not quite so prominent is M13 in Hercules top far left.
And, it may be my imagination, but there is a faint dot where M3 should be to the left of Canes Ventici, low middle left, just a wee bit above the right hand slope of the hill on the left.
Other constellations clearly visible are Corona Borealis just above the the aurora to the left of the lefthand hill with Bootes embedded in the glow above the lefthand hill. Auriga is above the righthand end of the aurora. Triangulum is above and a bit to the right of the moon with Aries below half way to Jupiter. To the right of Aries the far right clear area is occupied by Pisces.

What a superb panorama it is !

Malcolm.