Tuesday, June 12, 2012

Ancient Rainfall, Carved in Stone

"Stalactites grow from cave ceilings not as dull cones but often sporting elegant corrugations. In Physical Review Letters, two Italian researchers now explain these mysterious, wavy patterns using standard fluid mechanics. Their theory shows that the horizontal ripples form because spatially periodic patterns arise in the rate of mineral deposits from the water flowing down the stalactite. Starting from this model, climate scientists might in the future use stalactite surface structure to reconstruct variations in precipitation patterns over tens of thousands of years."Ancient Rainfall, Carved in Stone

Friday, June 1, 2012


"Uturuncu, or Uturunku, the highest summit in southwestern Bolivia, is astratovolcano. ...Researchers have determined that a large, roughly circular "disc" of land surrounding the volcano, approximately 70 km across, has been rising at a rate of 1 to 2 cm per year since at least the early 1990s, making it "one of the fastest uplifting volcanic areas on the Earth"." http://en.wikipedia.org/wiki/Uturuncu
and also: Temen que supervolcán Uturuncu se prepare para explotar en Bolivia

NCG 891

Another superb image at http://apod.nasa.gov/apod/ap120526.html
" This sharp cosmic portrait features NGC 891. .. At first glance, it has a flat, thin, galactic disk and a central bulge cut along the middle by regions of darkobscuring dust. The combined image data also reveal the galaxy's young blue star clusters and telltale pinkish star forming regions. And remarkably apparent in NGC 891's edge-on presentation are filaments of dust that extend hundreds of light-years above and below the center line. The dust has likely been blown out of the disk by supernova explosions or intense star formation activity. "
Here the NASA image after processing with AstroFracTool and Iris

Transit of Mercury

Very beautiful image at http://apod.nasa.gov/apod/ap120527.html Image Credit: SOHO - EIT Consortium, NASA
"The diminutive disk of Mercury, the solar system's innermost planet, spent about five hours crossing in front of the enormous solar disk in 2003 ... the horizon was certainly no problem for the sun-staring SOHO spacecraft. Seen as a dark spot, Mercury progresses from left to right (top panel to bottom) in these four images from SOHO's extreme ultraviolet camera. The panels' false-colors correspond to different wavelengths in the extreme ultraviolet which highlight regions above the Sun's visible surface."
Here the image from NASA after processing with IRIS

Transit of Venus

"The next transit of Venus, where Venus appears as a dark spot in front of the Sun, will begin at 22:09 UTC on 5 June 2012, and will finish at 04:49 UTC on 6 June.[1] Depending on the position of the observer, the exact times can vary by up to ±7 minutes. Transits of Venus occur in pairs that are eight years apart: theprevious transit was in June 2004, and the next pair of transits will occur in December 2117 and December 2125." from Wikipedia

Aristarchus proposed to measure the distance to the Sun using parallax. This approach based on the geometric principles of parallax last for two thousands of years, until Edmond Halley in 1716 proposed to observe the transit of Venus. The use of Venus transits gave an estimate of 1.53×10^13 cm, 2.6% above the currently accepted value, that of l.49 × 10^13 cm. More recently, in 1910, the parallax was measured using the asteroid Eros that passed much closer to Earth than Venus. A transit of Venus happens when this planet passes directly between the Sun and Earth, appearing as a small black disk moving across the Sun bright disk. The duration of such transits is usually measured in hours.
Read more "Two amateur astronomers at Berkeley", athttp://arxiv.org/abs/1202.0950