Sunday, February 19, 2017

A Rare View of the Moon

NASA's Deep Space Climate Observatory (DSCOVR) took this image and accompanying video of the Moon painted by direct sunlight. It looks like a Photoshop compilation, but it's genuine.  It's a universe of wonders out there!  





Tuesday, February 14, 2017

The Awesome Dunkleosteus

I've posted on this before, but I like to reconnect every once in a while with the most awesome prehistoric animal except for my first love, T. rex.  Dunkleosteus terrelli OWNED the seas of the Devonian, "The Age of Fishes."

I maintain the most popular page on the Dunk, here on Facebook.  Over 1,000 Dunk lovers have joined me.

Oddly, there is no book devoted to Dunkleosteus at any level.  It makes several appearances in fiction and popular culture, but it's still getting no respect compared to so many other prehistoric predators. That's a shame.  At a good 8 meters long (claims of 9 or 10 meters don't appear well-supported), the Dunk was a predator the likes of which the oceans never saw until the rise of the great marine reptiles.  The giant biting plates, so sharp one paleontologist said he could practically see himself in them today, constituted an implement of destruction never equaled since. We are talking about the functional equivalent of great sharpened fangs, only the size of traffic cones. The teeth of Megalodon or T. rex or Smilodon never came close.  With a head and forebody protected by bone some 5cm thick and with bone rings around the eyes, everything about the Dunk was built for combat.

Combat with what?

Once a Dunk grew to, say, 4 or 5 meters, the sharks of the day would not have been a threat.  Neither would the lesser placoderms,  Only other Dunks would have provided major competition. While paleozoologist Dr. Darren Naish once politely rebuked me for simplifying things down to "placoderms invented sex," they were the first vertebrates we know of to have male-female internal fertilization.  Did males compete for females? We don't know, but a clash between two armored submarines 8 m long must have been a terrifying spectacle.

Everything about the Dunk is scary, mysterious, or just plain awesome.  I hope you'll join me in following news of the study of this predator on Facebook and elsewhere.

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My daughter Lauryn photographed this Dunk at the University of Nebraska museum.

Part of my collection of Dunk models and memorabilia.




Saturday, February 11, 2017

International Day of Women and Girls in Science

What are you doing to encourage the women and girls you know to learn about the universe?



The Snake on the Milk Carton

OK, the long-missing Cropan's boa of Brazil , the rarest boa in the world, was not put on milk cartons, but it was put on posters nailed up all over the Atlantic Forest area.  The snake hadn't been seen alive since the 1950s when two farmers practically tripped over one as they walked the dirt road to work.  They had seen the poster, so they grabbed the 1.7-meter snake and contacted scientists via WhatsApp information on the posters!   Herpetologists had searched the area many times without result.




The handsome female snake, basically brown with black and darker brown markings, was released with a radio tag attached.  The boas, closely related to the pythons, currently count 43 species. We are constantly finding new snake species (31 in 2011) but this rediscovery was celebrated just as much.

Tuesday, February 07, 2017

Note on the Van Allen belts

In the book The First Space Race, Erika Vadnais and I discussed the discovery by Jame Van Allen and his team of the lower Van Allen belt in early 1958 by a particle detector placed on the Explorer 1 satellite.  There are now known to be two belts, varying in thickness and intensity based on natural events (the Sun pouring out an increased volume of energetic particles) or human-made events ("pumping the Van Allen belts"), an effect most famously seen in the Starfish Prime nuclear test of 1962, which degraded or destroyed several satellites.  In 2013, NASA announced the discovery of a third belt.  The this belt was outside the other two, appeared only when a solar prominence had unleashed a very large flow of particles, and lasted up to four weeks.  It was once feared astronauts could be launched only through the polar regions, where the belt effects were weak or absent, but limiting astronauts' time in orbit and restricting them to an orbital altitude above or below the inner belt works, too.  Only the Apollo astronauts transited the outer belt, and they punched through it rapidly on their way to and from the Moon, limiting the exposure time and thus the exposure in rads to to a level that was survivable.  




Van Allen belts (in yellow) in 2013 illustration released by NASA's Goddard Space Flight Center 

 See:
Wiley J. Larson and James R. Wertz (Editors), Space Mission Analysis and Design, 3rd Edition, Section 8.2, "Hardness and Survivability Requirements," 1 October 1999.
Fox, Karen. “NASA's Van Allen Probes Discover a Surprise Circling Earth,"
NASA press release, 28 February 2013.

Bille and Lishock, The First Space Race (Texas A&M), 2004.