Category Archives: Sky
the sky opens wide at night
the solar dance: the three-dimensional solar and galactic bodies we move within
Skydance
Have you been enjoying the crescent moon this week? It’s a bit bigger each night, as it moves away from its monthly passage between earth and the sun.
A week or so ago, early risers were treated to a crescent just about this same size, as the moon approached the sun from the other side – it was to the right of the sun as we see it in the sky here in the northern hemisphere, whereas now it’s to the left of the sun.
I missed the show, but those who woke a couple hours before dawn got to see the moon join a lineup of celestial delights: the Pleiades, Venus, Jupiter, and Betelgeuse (one of Orion’s shoulders).
For those in Europe, though, the morning held a special treat: the moon passed directly in front of Jupiter (an “occulation”). That peaceful ol’ moon moves fast through the starry sky: just about its own diameter each hour, constantly sliding past stars and planets along its way. Just a few minutes after it zoomed by Jupiter, Christian Fattinnanzi caught an absolutely beautiful dance of five moons, a gas giant, and wispy clouds:
Here we see Jupiter and all four Galilean moons (the ones Galileo spotted with his telescope, and visible similarly to his view in any pair of modern binoculars): Calisto, Ganymede, Io, and Europa. Lovely!
The living sky
The Earth lives within the larger body of the solar system; every planet a uniquely marvelous manifestation of minerals and gasses, with perhaps some liquid and frozen components or molten rock and volcanism cracking through the surface, each world alive and dynamic in its own ways. One of Earth’s many wonders is its incredibly dynamic atmosphere; winds carrying seeds and weather and scents, clouds shifting shape from moment to moment and changing color as they slip through the edges of the day and night, stars sprinkled and spinning across the night sky. At the highest latitudes, where the nights are long and cold, and the highest altitudes, the atmosphere thinning to nearly nothing, the earth’s physicality is expressed in subtle electromagnetic fields, which come alive in dancing waves of light, enlivened ions given color and motion when our local star exhales great gusts of itself in waves of charged particles that sweep past our tiny home of earth, water, fire, and air.
In the past couple of years, several filmmakers have been producing stunning time-lapse films of the natural world, utilizing high-definition cameras, sensitive digital CCDs, and sometimes even slow cinematography-style tracking shots. Today, I came across (thanks, Dish) the most compelling northern lights film I’ve yet to see; the sheer beauty of the motion and color, as well as a welcome variety of tones and intensities, kept me riveted through the entire five minutes (which, sadly, is quite an accomplishment for online video!).
The one time I was lucky enough to experience a full ribbons-of-light-overhead aurora display, in my backyard in Old Town, Maine in the winter of 1980-81, I likened it to a visual version of the rippling sounds of the Mahavishnu Orchestra….this film captures that blend of fluidity and surprise, intense dynamics, and sheer wonder like no other I’ve seen:
Comet Lovejoy blazes through sun’s corona
Something amazing happened tonight: a tiny comet skimmed just above the surface of the sun. Yeah, this happens pretty regularly, as we noted awhile back, but this one was special: an amateur astronomer Terry Lovejoy of Australia spotted the inbound comet about 2 weeks ago, giving astronomers worldwide plenty of time to train their sites on it as it blew ’round the sun. No one knew if it would survive its closest approach, which occurred at about sunset here in New Mexico.
SOHO, the space-based solar observatory, caught this sequence of its approach (the video covers almost 4 days):
While the brightness might make you think this is a giant comet, what you’re seeing is a cometary glow that blows out the sensitive CCD sensors, which are meant to help resolve the subtle, faint structures in the sun’s corona (which you can see dancing around in the images). The actual sun diameter is the inner circle; the outer circle blocks the brightest corona so the cameras can watch the outer corona. This comet was about 200m in diameter; while it’s the largest of over 2000 sun-grazing comets seen since SOHO launched in 1996, this is still puny by cometary standards – the small but very close Hyakutake was about 2km (2000m) in diameter, Halley’s is about 15km, and Hale-Bopp about 40km. Still, late this afternoon, the comet was brighter than the brightest stars or planets, though too close to the sun to be seen with the naked eye.
And tonight, this amazing video came in from the Solar Dynamics Observatory, showing the comet apparently surviving perihelion, whizzing through the solar corona. It passed only 140,000km above the sun’s surface: that’s just ten or so earth-diameter! Yoswa. (the video loops three times, each time in slower motion)
I tell ya, we’ve got some pretty darn amazing eyes on the skies these days! (Here’s another view of the closest passage, offering a wider perspective, and here’s the SOHO view from the next morning, showing the tail left behind as the comet emerges and heads back out away from its hairy close encounter with our star.)
For more images and a complete run-down on the approach and passage of Comet Lovejoy, check out AstroBob’s day-of coverage and his posts in the few days before and after.
UPDATE, 12/22/11: Not only did our little hero survive, but it’s putting on a nice, though subtle, morning show in the southern hemisphere. The tail is 15 degrees long, about half of which is visible to the naked eye just before sunrise; as always, cameras bring out the detail with slightly longer exposure times. Here’s one from Colin Legg of Mandurah, Western Australia, recently posted on SpaceWeather.com:
Wow! Sun-diving comet and coronal mass ejection
More often than you might imagine, tiny comets get sucked into the sun’s massive gravitational vortex, and die sparkling little deaths as “sun-divers.” In recent years, the SOHO satellites, which are constantly watching the sun, have shown us the final hours of these fragments of the distant outer solar system. Well, this week, just after a sun-diver met its fate, a pretty darn impressive coronal mass ejection blew out of the sun:
About the movie above: first, it may take a short while for it to fully load, but once it does, it will continue to repeat itself. It shows a 9-hour period late on October 1st. The white circle is the actual size of the sun; the larger masked area simply blocks out most of the bright solar corona, so the subtler dynamics of the outer corona can be imaged. The coronal mass ejection seen here is not unusual, or especially large; during the more active years in the sun’s 11-year solar activity cycle, such eruptions occur anywhere from daily to weekly.
A click on the image will take you to the SpaceWeather.com page from which I grabbed this, where you can read a bit about whether this reaction we see above is a coincidence, and follow a couple links to a smaller but surprisingly clear event last summer that first opened the question: could a tiny comet actually trigger a solar reaction? Apparently, the idea isn’t considered as outlandish as it once was.
But beyond the new science that may be emerging, this little movie gives us a chance to simply revel in the dynamic beauty that is our local star.
Bright Blue Ball (spinning spinning free) 