Please vote for the TWO best Astronomy Pictures of the Day (image and text) of October 23-29, 2011.
(Repeated APODs are not included in the poll.)
All titles are clickable and link to the original APOD page.
We ask for your help in choosing an APOW as this helps Jerry and Robert create "year in APOD images" review lectures, create APOM and APOY polls that can be used to create a free PDF calendar at year's end, and provides feedback on which images and APODs were relatively well received. You can select two top images for the week.
We are very interested in why you selected the APODs you voted for, and enthusiastically welcome your telling us why by responding to this thread.
Thank you!
_______________________________________________________________
<- Previous week's poll
What powers the Heart Nebula? The large emission nebula dubbed IC 1805 looks, in whole, like a human heart. The nebula glows brightly in red light emitted by its most prominent element: hydrogen. The red glow and the larger shape are all created by a small group of stars near the nebula's center. A close up in high dynamic range (HDR) spanning about 30 light years contains many of these stars is shown above. This open cluster of stars contains a few bright stars nearly 50 times the mass of our Sun, many dim stars only a fraction of the mass of our Sun, and an absent microquasar that was expelled millions of years ago. The Heart Nebula is located about 7,500 light years away toward the constellation of Cassiopeia.
A fourth moon is visible on the above image if you look hard enough. First -- and furthest in the background -- is Titan, the largest moon of Saturn and one of the larger moons in the Solar System. The dark feature across the top of this perpetually cloudy world is the north polar hood. The next most obvious moon is bright Dione, visible in the foreground, complete with craters and long ice cliffs. Jutting in from the left are several of Saturn's expansive rings, including Saturn's A ring featuring the dark Encke Gap. On the far right, just outside the rings, is Pandora, a moon only 80-kilometers across that helps shepherd Saturn's F ring. The fourth moon? If you look closely in the Encke Gap you'll find a speck that is actually Pan. Although one of Saturn's smallest moons at 35-kilometers across, Pan is massive enough to help keep the Encke gap relatively free of ring particles.
Young suns still lie within dusty NGC 7129, some 3,000 light-years away toward the royal constellation Cepheus. While these stars are at a relatively tender age, only a few million years old, it is likely that our own Sun formed in a similar stellar nursery some five billion years ago. Most noticeable in the sharp image are the lovely bluish dust clouds that reflect the youthful starlight. But the compact, deep red crescent shapes are also markers of energetic, young stellar objects. Known as Herbig-Haro objects, their shape and color is characteristic of glowing hydrogen gas shocked by jets streaming away from newborn stars. Paler, extended filaments of reddish emission mingling with the bluish clouds are caused by dust grains effectively converting the invisible ultraviolet starlight to visible red light through photoluminesence. Ultimately the natal gas and dust in the region will be dispersed, the stars drifting apart as the loose cluster orbits the center of the Galaxy. At the estimated distance of NGC 7129, this telescopic view spans about 40 light-years.
As northern hemisphere nights grow longer, October is a good month for spotting auroras, or even other eerie apparitions after dark. And this week the night sky did not disappoint. On October 24th a solar coronal mass ejection impacted planet Earth's magnetosphere triggering far ranging auroral displays. On that night, this dramatic silhouette against deep red and beautiful green curtains of shimmering light was captured near Whitby, Ontario, Canada. But auroras were reported even farther south, in US states like Alabama, Kansas, and Oklahoma at latitudes rarely haunted by the northern lights. Well above 100 kilometers, at the highest altitudes infused by the auroral glow, the red color comes from the excitation of oxygen atoms.
<- Previous week's poll