Strictly Astronomy
RSSReanimating the 1882 Transit of Venus
“In late 1882, Massachusetts astronomer David Peck Todd traveled to California to photograph the transit of Venus from the summit of Mount Hamilton, where a solar photographic telescope made by the renowned optical firm Alvan Clark & Sons waited among the stacks of bricks and timbers from which Lick Observatory was rising. As the transit unfolded on December 6th, Todd obtained a superb series of plates under perfect skies. His 147 glass negatives were carefully stored in the mountain vault, but as astronomers turned to other techniques for determining the scale of the solar system… the plates lay untouched and were eventually forgotten.”
“Fast-forward 120 years. Spurred by a reference in one of Todd’s letters in Lick’s Mary Lea Shane Archives, Bill Sheehan and I found all 147 negatives, still in good condition, at the observatory. To our knowledge, this collection of photos constitutes the most complete surviving record of a historical transit of Venus.”
“Digital imaging technology made reanimating Todd’s transit images a comparatively simple undertaking. The result, which premiered at the International Astronomical Union’s general assembly in Sydney in July 2003, shows Venus’s silhouette flickering strangely as it marches across the Sun’s face. It’s the shadow-show of an astronomical event that occurred when Queen Victoria sat on the throne of Great Britain and Chester Arthur was president of the United States — a moving record of an event seen by no one now living, and a preview of what millions will see for the last time in their lives on June 5-6, 2012.”
(This animation is a good preview of what we will see in about ten days as Venus crosses the visible disk of the Sun for the last time for almost 130 years. I will be posting more information about this as the time approaches. -JCB)
Is ‘Planet X 2.0’ Lurking Beyond Pluto’s Orbit?
Before the doomsayers hijacked “Planet X” and used it as a phantom (a.k.a. “Nibiru”) to scare people into believing the 2012 doomsday hype, the hunt for Planet X was an exciting astronomical quest to find a hypothetical world in the outermost reaches of the solar system in the early 20th century.
Although dwarf planet Pluto was discovered during the search for Planet X in 1930, apparently ending the quest, there is enduring evidence for the existence of a substantial planet gravitationally shaping the population of minor bodies in the Kuiper belt and beyond. The only problem is, we can’t see it.
On (And Near) The Center-Line: The 20th May annular solar eclipse from Utah
Kanarraville, Utah was very close to the center-line of Sunday’s eclipse, meaning that it was nearest to the center of the darkest shadow cone produced by the Moon as it crossed the face of the Sun. In this image, the disk of the Sun (red) perfectly frames the shadowed outline of the Moon at mid-eclipse. Compare with the photo below, taken from Zion National Park (about 18 miles southeast of Kanarraville) at the same time.
(Credit: G.A. Esquerdo)
The location of the two sites is shown on the map below. The red line is the eclipse center-line; Kanarraville is very close to where the red line crosses the thick orange line indicating Interstate 15. Zion is at bottom-center.
Even though the moon is about 240,000 miles away, a linear difference of 18 miles on the surface of the Earth is sufficient to noticeably shift the apparent position of the Moon in the sky. This becomes crucial in total solar eclipses, when the region in which the eclipse is total may be only a few miles in width.
Annular eclipses occur when the Moon is slightly further away from the Earth than on average; when it is closer than average, the solar disk is completely blocked and a total eclipse occurs. The next annular eclipse is on May 10, 2013.
Solar Eclipse from Kanarraville, UT. May 20th, 2012
Credit: by-tor
May 20th Annular Solar Eclipse From West Texas
(Credit: Rachel Walker/University of Texas/McDonald Observatory)
Kepler telescope studies star superflares
NASA’s Kepler space telescope has provided fresh insight on the colossal explosions that can afflict some stars.
(A superflare would be associated with very large starspots - much larger than those on the Sun.)
“These enormous releases of magnetic energy - known as superflares - could damage the atmosphere of a nearby orbiting planet, putting at risk any lifeforms that might reside there. Fortunately, Kepler shows superflares to be much less frequent on slow-rotating stars like our Sun. The new observations are reported in the journal Nature.”
“Hiroyuki Maehara from Kyoto University, Japan, and colleagues have now reviewed the data to compile the best statistics yet on the frequency and size of superflares. Kepler saw a total of 365 superflares during an observation period lasting 120 days. The numbers confirm that very few (only 0.2%) Sun-like stars experience monster flares.”
Penn astrophysicists zero in on gravity theory
Most people take gravity for granted. As scientists have been able to see farther and deeper into the universe, the laws of gravity have been revealed to be under the influence of an unexplained force.
(A galactic image taken by the Hubble Space Telescope. Galaxies like this one “screen” the effect of a hypothetical fifth force. CREDIT: NASA)
“By innovatively analyzing a well-studied class of stars in nearby galaxies, [Pennsylvania astrophysicist Bhuvnesh]Jain and his colleagues — Vinu Vikram, Anna Cabre and Joseph Clampitt at Penn and Jeremy Sakstein at the University of Cambridge — have produced new findings that narrow down the possibilities of what this force could be. Their findings, published on the Arxiv, are a vindication of Einstein’s theory of gravity. Having survived a century of tests in the solar system, it has passed this new test in galaxies beyond our own as well.”
“In 1998, astrophysicists made an observation that turned gravity on its ear: theuniverse’s rate of expansion is speeding up. If gravity acts the same everywhere, stars and galaxies propelled outward by the Big Bang should continuously slow down, like objects thrown from an explosion do here on Earth.”
“This observation used distant supernovae to show that the expansion of the universe was speeding up rather than slowing down. This indicated that something was missing from physicists’ understanding of how the universe responds to gravity, which is described by Einstein’s theory of general relativity. Two branches of theories have sprung up, each trying to fill its gaps in a different way.”
“One branch — dark energy — suggests that the vacuum of space has an energy associated with it and that energy causes the observed acceleration. The other falls under the umbrella of “scalar-tensor” gravity theories, which effectively posits a fifth force (beyond gravity, electromagnetism and the strong and weak nuclear forces) that alters gravity on cosmologically large scales.”
”’We’ve been able to perform a powerful test using just 25 nearby galaxies that is more than a hundred times more stringent than standard cosmological tests… We find consistency with Einstein’s theory of gravity and we sharply narrow the space available to these other theories. Many of these theories are now ruled out by the data,’ Jain said.”
(We still don’t really have any idea what ‘dark energy’ is, even as these new results seem to rule out alternatives that simply modify the known theory of gravitation. Some suggest that it is a manifestation of ‘zero-point fluctuations’ of the vacuum of space itself. Regardless, we are still a long way from a complete understanding of this phenomenon. -JCB)
Still Thinking About That Astronomy Career?
It may be worth the buy-in cost of education. But such a decision comes with one major caveat: the rate of creation of new, permanent jobs in astronomy/astrophysics/planetary science is at or near zero. It’s not clear where the 11% “projected ten-year growth” in the graphic is coming from, unless temporary, “soft money” positions — where the real ‘growth’ in astronomy is happening — are included.
The good news: The training one gets in academic astronomy makes for skills marketable in many other areas from financial services to intelligence analysis. Astronomers graduate with some hefty problem-solving skills, and those leaving the field find employment in some pretty diverse sectors of the economy.
(Source: National Center for Educational Statistics and Yahoo calculator for 750 professions)
A Gallery Of May 20 Annular Solar Eclipse Images
1. The sun sets behind a barn and windmill on Sunday, May 20, 2012, southwest of Ellis, Kansas, during a partial solar eclipse. Credit: Steven Hausler, The Hays Daily News / AP
2. An annular solar eclipse appears in the sky over Yokohama near Tokyo Monday, May 21, 2012. Credit: AP / SL
3. A view of partial solar eclipse, seen through a black film in Srinagar, India, in January 2011. Credit: Mukhtar Khan/AP/Canadian Press
4. An annular solar eclipse appears during a break in clouds over Taipei, Taiwan, Monday, May 21, 2012. Credit: Wally Santana / AP
5. An annular solar eclipse appears in Fujisawa, near Tokyo, Monday, May 21, 2012. Credit: AP
6. A partial annular solar eclipse appears through construction scaffoldings in Beijing, China, Monday, May 21, 2012. Credit: Ng Han Guan / AP
The partially-eclipsed Sun in projection. Washburn Observatory, Madison, WI, 20 May 2012.
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