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Negli strati superiori dell’atmosfera il vapor acqueo, un potente gas ad effetto serra, stà diminuendo ; uno studio basato su osservazioni della NASA ci spiega il perchè e le conseguenze!

Watts Up With That?

Guest post submitted by Ken Gregory, Friends of Science.org

An analysis of NASA satellite data shows that water vapor, the most important greenhouse gas, has declined in the upper atmosphere causing a cooling effect that is 16 times greater than the warming effect from man-made greenhouse gas emissions during the period 1990 to 2001.

The world has spent over $ 1 trillion on climate change mitigation based on climate models that don’t work. They are notoriously poor at simulating the 20th century warming because they do not include natural causes of climate change – mainly due to the changing sun –  and they grossly exaggerate the feedback effects of greenhouse gas emissions.

Most scientists agree that doubling the amount of carbon dioxide (CO2) in the atmosphere, which takes about 150 years, would theoretically warm the earth by one degree Celsius if there were no change in evaporation, the…

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credit :Nasa Explorer

evaluation to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation and analyze 2249 world- wide monthly temperature records from GISS (NASA) with the 100-year period covering 1906-2005 and the two 50-year periods from 1906 to 1955 and 1956 to 2005.

Watts Up With That?

Since we have been paying a lot of attention to the surface record given the recent revelations surrounding the adjustments to data and NOAA’s release of the State of the Climate  Report claiming that the USA had the hottest year ever (but the globe did not) this paper seems like a good one to review.

How Natural is the Recent CentennialWarming? An Analysis of 2249 Surface Temperature Records

Horst-Joachim Lu¨decke, Rainer Link, and Friedrich-Karl Ewert

EIKE, European Institute for Climate and Energy, PO.Box 11011, 07722 Jena, GERMANY

Abstract. We evaluate to what extent the temperature rise in the past 100 years was a trend or a natural fluctuation and analyze 2249 world- wide monthly temperature records from GISS (NASA) with the 100-year period covering 1906-2005 and the two 50-year periods from 1906 to 1955 and 1956 to 2005. No global records are applied. The data document a strong…

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 WASHINGTON — Using computer simulations, scientists from the NASA Astrobiology Institute team at the University of Hawaii are shedding light on a question that has challenged astronomers for years: What causes wide binary stars?

Binary stars are pairs of stars that orbit each other. Wide binary stars are separated by as much as one light-year in their orbits, farther apart than some stellar nurseries are wide. Astronomers have known about such distant pairs for a long time but have not understood how they form.

Researchers simulated the complex motions of newborn triple stars still embedded in their nascent cloud cores. They studied the motions 180,000 times and concluded the widest binary systems began as three stars, not just two. This research appears in a paper to be published in the Dec. 13 issue of the journal Nature and was released last week online.

Most stars are born in small, compact systems with two or more stars at the center of a cloud core. When more than two stars share a small space, they gravitationally pull on each other in a chaotic dance. The least massive star often is kicked to the outskirts of the cloud core while the remaining stars grow larger and closer by feeding on the dense gas at the center of the cloud core.

If the force of the kick is not forecful enough, the runt star will not escape, but instead begin a very wide orbit of the other two, creating a wide binary. However, sometimes astronomers find only two stars in a wide binary. This means either the star system formed differently or something happened to one of the original binary pair.
“What may have happened is that the stars in the close binary merged into a single larger star,” said the paper’s lead author, Bo Reipurth of the Institute for Astronomy at the University of Hawaii at Manoa. “This can happen if there is enough gas in the cloud core to provide resistance to their motion. As the two stars in the close binary move around each other surrounded by gas, they lose energy and spiral toward each other. Sometimes there is so much gas in the core that the two close stars spiral all the way in and collide with each other in a spectacular merging explosion.”

The wide binary nearest to Earth is Alpha Centauri. The star itself is a close binary. Alpha Centauri has a small companion, Proxima Centauri, which orbits at a distance of about one-quarter of a light-year, or 15,000 times the distance between Earth and the sun. All three stars were born close together several billion years ago, before a powerful dynamic kick sent Proxima out into its wide path, where it has been orbiting ever since.
NASA’s Kepler mission already has proven that more than one planet can form and persist in the stressful realm of a binary star, a testament to the diversity of planetary systems in our galaxy.

NASA supported the University of Hawaii work through a cooperative agreement with NASA’s Ames Research Center, Moffett Field, Calif., and the NASA Astrobiology Institute, which is a partnership between NASA, 15 U.S. teams, and 10 international consortia. The research on wide binary stars included the University of Turku in Finland.

       Credit J.D. Harrington,  Karen Jenvey,  Rachel Hoover, Louise Good

further more at:

http://astrobiology.nasa.gov

Chandra :: Photo Album :: N63A :: 19 Dec 03

viaChandra :: Photo Album :: N63A :: 19 Dec 03.