Salutations celestial sight seers!
I'm David Fuller, welcome to Eyes on the Sky; what's up this week?
Our Sun is a largely stable, G-spectral class dwarf star that basically does a nice job
for life on Earth by being like a Goldilocks-type star: Not too hot, not too cold, but JUST
RIGHT for where Earth revolves around the Sun.
And it's been doing that for billions of years too, though it will increase enough in temperature
800 million years from now to boil off all the water in our oceans.
So... get your spaceships ready!
Okay, but seriously, various views of stars are a lot of what gets discussed her on Eyes
on the Sky, and what better way to observe a star than to look at the CLOSEST one to
us?
Of course, there are a number of safeguards to avoid damaging your eyes, which you can
learn about in a video I made last year about solar viewing safety.
Two points I will reiterate here though: Please, DO NOT use the screw-on eyepiece filters,
which can crack and allow unfiltered sunlight to pass through, and ALWAYS use either approved
visual use filters or #14 welder's glass ONLY for solar observing.
So what to look for?
First of all, sunspots.
These are darker regions on the photosphere of the Sun, which appear this way because
they are cooler than the surrounding areas by 1300 to 2800 hundred degrees kelvin.
They are caused by intense magnetic fields, and often come in pairs, with the two poles
of the magnetic field making up the pair of sunspots.
Sometimes they are small, but many can be larger than the size of Earth!
And for the largest ones, you do not even need a telescope -- holding up a solar filter
over your eyes may be enough to see the largest ones.
Typically, sunspots are seen along two regions above and below the Sun's equator, and rotate
across the surface.
The Sun's rotational period is just over 25 days, so many sunspot groups are visible for
up to 2 weeks at a time, and may even reappear after passing around the opposite side.
Though a significant level of sunspot activity peaked in 2011, the actual peak for sunspots
should occur later this year, providing observers with a "double peak" of activity that started
in 2011 that may continue, and re-peak in 2013.
Even if the second peak fails to materialize, we are still witnessing around 50+ sunspots
per month presently.
Dark Sky Fact: A sunset glow has red-shifted light; this helps your body recognize night-time
coming.
But computer screens have blue-shifted light so download the free program f.lux to automatically
change your computer screen every day to red-shifted light when the light outside does: At sunset.
Another feature to look for is faculae.
Instead of dark areas on the surface like sunspots, faculae are brighter areas that
are also associated with magnetic fields.
They are often around or near sunspots, but sunspots are not required for them to be present.
Faculae are often easier to see near the limb of the sun, but very bright ones may be seen
in the center as well.
Often they can be quite subtle, and initially not as easy to see as sunspots.
One of the most dramatic ways to view the sun though, is with a telescope that has a
special Hydrogen-alpha filter.
These are quite a bit more expensive than regular visual filters, because they are tuned
to a very specific wavelength of light that allows us to see solar flares and prominences
along the Sun's limb.
Because telescopes and filters that do that start in the $700 to $1000 range (and up!),
many of us do not have them, but you can still see those prominences on the sun -- I'll have
a link at EyesontheSky.com where you can see the Sun at various wavelengths of light.
The best part about observing the Sun is that it is always changing -- there is always something
new and different to see, even day to day.
Along The Ecliptic: Saturn is stationary on July 9, and over the course of several days
you can see how little it moves compared to Kappa Virginis.
The Moon will be 7 degrees from Venus on the 10-th; look for this pairing about an hour
after sunset local time.
That's all for this week.
Keep your eyes on the sky and your outdoor lights aimed down, so we can all see, what's
up.
I'm David Fuller, wishing you clear and dark skies.