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Saturday Lecture Series: Noctilucent Clouds

by coldwarrior ( 31 Comments › )
Filed under Academia, Astronomy, Open thread, saturday lecture series, Science at June 4th, 2011 - 8:30 am

I have seen Noctilucent Clouds as far south as southern West Virginia.  They can be seen even farther south.

 

 

Noctilucent: Illuminated at night.

 

Every spring and early summer Noctilucent clouds are visible in the higher latitudes due to this phenomenon:

 

 

NOCTILUCENT CLOUDS OVER EUROPE: The 2011 noctilucent cloud (NLC) season has begun. For the past few nights, observers across northern Europe have spotted velvety, electric-blue tendrils rippling across the sunset sky.

 

Observing tips: Look west 30 to 60 minutes after sunset when the Sun has dipped 6o to 16o below the horizon. If you see luminous blue-white tendrils spreading across the sky, you’ve probably spotted a noctilucent cloud. Although noctilucent clouds appear most often at arctic latitudes, they have been sighted in recent years as far south as Colorado, Utah and Virginia. NLCs are seasonal, appearing most often in late spring and summer. In the northern hemisphere, the best time to look would be between mid-May and the end of August.

NASA is working to understand this phenomenon:

The Aeronomy of Ice in the Mesosphere (AIM) satellite mission is exploring Polar Mesospheric Clouds (PMCs), also called noctilucent clouds, to find out why they form and why they are changing.

The AIM mission has been extended by NASA through the end of FY12. During this time the instruments will monitor noctilucent clouds to better understand their variability and possible connection to climate change. Individual instrument data collection status, as well as spacecraft and instrument health, will be monitored throughout the life of the mission and reported periodically on this website.

The primary goal of the AIM mission is to help scientists understand whether the clouds’ ephemeral nature, and their variation over time, is related to Earth’s changing climate – and to investigate why they form in the first place. By measuring the thermal, chemical and other properties of the environment in which the mysterious clouds form, the AIM mission will provide researchers with a foundation for the study of long-term variations in the mesosphere and its relationship to global climate change. In addition to measuring environmental conditions, the AIM mission will collect data on cloud abundance, how the clouds are distributed, and the size of particles within them.

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Posted in Academia, Astronomy, Open thread, saturday lecture series, Science | 31 Comments »

Saturday Lecture Series: Stormy Saturn

by coldwarrior ( 38 Comments › )
Filed under Academia, Astronomy, Open thread, saturday lecture series, Science at May 21st, 2011 - 8:00 am

This from our friends at NASA. This event on Saturn is visible through backyard telescopes, so good hunting!

May 19, 2011: NASA’s Cassini spacecraft and a European Southern Observatory ground-based telescope are tracking the growth of a giant early-spring storm in Saturn’s northern hemisphere so powerful that it stretches around the entire planet. The rare storm has been wreaking havoc for months and shooting plumes of gas high into the planet’s atmosphere.
Super Storm on Saturn (storm, 200px)
This false-color infrared image shows clouds of large ammonia ice particles dredged up by the powerful storm. Credit: Cassini. [more]

“Nothing on Earth comes close to this powerful storm,” says Leigh Fletcher, a Cassini team scientist at the University of Oxford in the United Kingdom, and lead author of a study that appeared in this week’s edition of Science Magazine. “A storm like this is rare. This is only the sixth one to be recorded since 1876, and the last was way back in 1990.”

Cassini’s radio and plasma wave science instrument first detected the large disturbance in December 2010, and amateur astronomers have been watching it ever since through backyard telescopes. As it rapidly expanded, the storm’s core developed into a giant, powerful thunderstorm, producing a 3,000-mile-wide (5,000-kilometer-wide) dark vortex possibly similar to Jupiter’s Great Red Spot.

This is the first major storm on Saturn observed by an orbiting spacecraft and studied at thermal infrared wavelengths. Infrared observations are key because heat tells researchers a great deal about conditions inside the storm, including temperatures, winds, and atmospheric composition. Temperature data were provided by the Very Large Telescope (VLT) on Cerro Paranal in Chile and Cassini’s composite infrared spectrometer (CIRS), operated by NASA’s Goddard Space Flight Center in Greenbelt, Md.

“Our new observations show that the storm had a major effect on the atmosphere, transporting energy and material over great distances — creating meandering jet streams and forming giant vortices — and disrupting Saturn’s seasonal [weather patterns],” said Glenn Orton, a paper co-author, based at NASA’s Jet Propulsion Laboratory in Pasadena, Calif.

The violence of the storm — the strongest disturbances ever detected in Saturn’s stratosphere — took researchers by surprise. What started as an ordinary disturbance deep in Saturn’s atmosphere punched through the planet’s serene cloud cover to roil the high layer known as the stratosphere.

“On Earth, the lower stratosphere is where commercial airplanes generally fly to avoid storms which can cause turbulence,” says Brigette Hesman, a scientist at the University of Maryland in College Park who works on the CIRS team at Goddard and is the second author on the paper. “If you were flying in an airplane on Saturn, this storm would reach so high up, it would probably be impossible to avoid it.”

A separate analysis using Cassini’s visual and infrared mapping spectrometer, led by Kevin Baines of JPL, confirmed the storm is very violent, dredging up deep material in volumes several times larger than previous storms. Other Cassini scientists are studying the evolving storm and, they say, a more extensive picture will emerge soon.

Stay tuned to Science@NASA for updates.

Editor: Dr. Tony Phillips | Credit: Science@NASA

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Posted in Academia, Astronomy, Open thread, saturday lecture series, Science | 38 Comments »

Saturday Lecture Series: The National Monarchies

by coldwarrior ( 40 Comments › )
Filed under Academia, History, Open thread, saturday lecture series at April 30th, 2011 - 8:00 am

Today we close out the Middle Ages and set the stage for the Renaissance in Europe. Professor Eugen Weber continues in:

24. The National Monarchies
A new urban middle class emerged, while dynastic marriages established centralized monarchies.

 

Dante, Papal Schisms, Jean D’Arc, and the rise of commerce/middle class and the city state pulls power from the landed gentry. The old feudal order is being replaced. From this chaos and change, the national monarchies are strengthened at the cost of the local barons. The modern map of Europe that we all can recognize is drawn in this time.

 

Follow the link out to the lecture.

 

 

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Posted in Academia, History, Open thread, saturday lecture series | 40 Comments »

Saturday Lecture Series: Full Moon at Perigee Tonight

by coldwarrior ( 85 Comments › )
Filed under Academia, Astronomy, Open thread, saturday lecture series, Science at March 19th, 2011 - 8:30 am

Good Morning all, today’s lecture covers some simple planetary mechanics and some great timing.

 

Terms:

perigee: point nearest to orbited object: the point in the orbit of a satellite, moon, or planet at which it comes nearest to the object it is orbiting [ Late 16th century. Via French < late Greek perigeion < perigeios “close round the earth” < Greek peri “around” + gē “earth” ]

apogee: point in orbit farthest from Earth: the point at which a satellite orbiting an astronomical object is farthest from the center of the object being orbited [ Late 16th century. < French < Greek apogaios “away from the Earth” < gaia “Earth” ]

 

From NASA:

 

 

Tonight, the full moon will be practically at perigee (off by one hour). The moon has two points for perigee and two points for apogee in each rotation around the Earth each 27.3 hours.

 

The Moon orbits the Earth in an ellipse with an eccentricity of about 0.05 where 0 is a perfect circle and 1.0 is a parabola. 0.05 equates to a perigee point that is 23,000 miles closer than apogee. Or, a 14% larger moon with 30% more brightness tonight.

 

 

From our Friends at NASA:

 

Super Full Moon:

March 16, 2011: Mark your calendar. On March 19th, a full Moon of rare size and beauty will rise in the east at sunset. It’s a super “perigee moon”–the biggest in almost 20 years.

“The last full Moon so big and close to Earth occurred in March of 1993,” says Geoff Chester of the US Naval Observatory in Washington DC. “I’d say it’s worth a look.”

Full Moons vary in size because of the oval shape of the Moon’s orbit. It is an ellipse with one side (perigee) about 50,000 km closer to Earth than the other (apogee): diagram. Nearby perigee moons are about 14% bigger and 30% brighter than lesser moons that occur on the apogee side of the Moon’s orbit.

Super Full Moon (movie strip, 550px) 

Above: Perigee moons are as much as 14% wider and 30% brighter than lesser full Moons. [video]

“The full Moon of March 19th occurs less than one hour away from perigee–a near-perfect coincidence1 that happens only 18 years or so,” adds Chester.

A perigee full Moon brings with it extra-high “perigean tides,” but this is nothing to worry about, according to NOAA. In most places, lunar gravity at perigee pulls tide waters only a few centimeters (an inch or so) higher than usual. Local geography can amplify the effect to about 15 centimeters (six inches)–not exactly a great flood.

Super Full Moon (moon illusion, 200px) 

The Moon looks extra-big when it is beaming through foreground objects–a.k.a. “the Moon illusion.”

Indeed, contrary to some reports circulating the Internet, perigee Moons do not trigger natural disasters. The “super moon” of March 1983, for instance, passed without incident. And an almost-super Moon in Dec. 2008 also proved harmless.

Okay, the Moon is 14% bigger than usual, but can you really tell the difference? It’s tricky. There are no rulers floating in the sky to measure lunar diameters. Hanging high overhead with no reference points to provide a sense of scale, one full Moon can seem much like any other.

The best time to look is when the Moon is near the horizon. That is when illusion mixes with reality to produce a truly stunning view. For reasons not fully understood by astronomers or psychologists, low-hanging Moons look unnaturally large when they beam through trees, buildings and other foreground objects. On March 19th, why not let the “Moon illusion” amplify a full Moon that’s extra-big to begin with? The swollen orb rising in the east at sunset may seem so nearby, you can almost reach out and touch it.

Don’t bother. Even a super perigee Moon is still 356,577 km away. That is, it turns out, a distance of rare beauty.

See the ScienceCast of this story on YouTube at: http://www.youtube.com/watch?v=r1yalg_Apdw
Author: Dr. Tony Phillips | Credit: Science@NASA

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So, if you are going to have some clear skies, it would be worth it to go outside tonight and get a glimpse of that perigee full moon. The full Moon rises at 1953L in the East.

 

 

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Posted in Academia, Astronomy, Open thread, saturday lecture series, Science | 85 Comments »

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