by VirtualAstro | Jan 23, 2012
Beginners Guide To Aurora
Here is a very quick beginners guide to explaining aurora
Aurora = The Northern (or Southern) lights/ Aurora Borealis/ Australis
Usually seen near the poles of the Earth, but can be seen further South in the UK or USA.
So how and where does it come from?
“Coronal Mass Ejection” = A load of solar material hurled out of the Sun. A big one can contain billions of tons of “plasma”.
Plasma hits Earth’s “magnetosphere” causing “geomagnetic storms” = Aurora, also known as the Northern or Southern lights.
Geomagnetic storms are measured using a scale called the “Planetary Kp index” ranging from 1 to 9. 1 being low and 9 being a very heavy storm.
The higher the Kp index the higher the likelihood of Aurora and the further South it can be seen. 5 = Scotland 8+ Southern England.
Geomagnetic storms and aurora are very unpredictable and forecasts can be very vague, we don’t know the intensity or where the aurora can be seen from until it hits.
Here is a link to NOAA Space Weather Scales
To watch the aurora, you only need your eyes, just like watching meteors or the International Space Station. Look North and low down on the horizon, it may be faint at first.
Solar Flare
by VirtualAstro | Sep 29, 2011
Sunset with the Massive Sun Spot 1302 (Upper left on the Sun) Credit: Adrian Scott
A highly active region on the Sun threatens to deliver powerful geomagnetic storms over the week ahead. Highly energetic solar eruptions are likely heading in our direction to give Earth’s magnetic field a significant glancing blow!
Over the past few days the new sunspot AR1302 has been incredibly active, hurling massive X-class solar flares into space and it will soon face Earth.
The massive sunspot, many times larger than the Earth (see images below) is expected to increase in size and energy, and is expected to release powerful solar flares, sparking strong geomagnetic storms. (more…)
by VirtualAstro | Jun 21, 2011
I took this image of the Solstice Sunset near my home in the UK last year, it was an amazing experience watching the sun sink below the horizon on the longest day.
Will we be lucky enough to be able to witness this wonder again this year and see some more great images?
by Steve Owens | Jun 13, 2011
Originally posted on Dark Sky Diary by Steve Owens (@darkskyman on twitter)
Today, 13 June, is one of only four days in the year when the time as read on a sundial will be exactly correct.
Sundials usually tell the time using the shadow of the gnomon as cast by the Sun. This is possible as the Sun appears to move across the sky at an approximately constant speed, and so the shadow of the gnomon also moves at an approximately constant speed. The inconstancy of the Sun’s apparent motion in the sky – and therefore of the gnomon’s shadow on a sundial – is the subject of this article, and is calculated using the Equation of Time.
If you look at the shadow of a sundial’s gnomon it will fall onto a curve of numbers, along hour lines indicating local solar time. This is not equal to the official clock time until three important corrections are made:
Please read the rest of this article on Dark Sky Diary
