Posts Tagged ‘stars’

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A Musical Clock made of Stars

February 6, 2012



Wheel of Stars

Jim Bumgardner: To make this, I downloaded public data from Hipparcos, a satellite launched by the European Space Agency in 1989 that accurately measured over a hundred thousand stars. The data I downloaded contains position, parallax, magnitude, and color information, among other things.

I used this information to plot the brightest stars, and cause them to revolve about Polaris (the North Star) very slowly, as the stars appear to do. Like the night sky, this is a sidereal time clock — it takes nearly 24 hours for the stars to fully rotate. You’ll notice some familiar constellations, such as the Big Dipper in there. As the stars cross zero and 180 degrees, indicated by the center line, the clock plays an individual note, or chime for each star. The pitch of the chime is based on the star’s BV measurement (which roughly corresponds to color or temperature). The volume is based on the star’s magnitude, or apparent brightness, and the stereo panning is based on the position on the screen (use headphones to hear it better).

Basically, this is a very literal kind of “music of the spheres,” and is typical of my projects, which often involve circles and music. This idea for making a music box out of stars was a natural progression from some previous projects of mine, like the Whitney Music Box, and Musical Chess, which you might also enjoy.

If you’d like a large, high fidelity Wheel of Stars to project on the ceiling of your home, gallery or museum, contact me. I’d be happy to provide you with software or suggestions.

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The Elements of ExoPlanets

February 2, 2012

By looking at the wavelengths of light from nearby stars, researchers have determined the abundance of certain elements for more than a hundred stars. Trace elements in such stars may influence their habitable zones, where planets with life might dwell.

A star’s energy comes from the combining of light elements into heavier elements in a process known as fusion. Our Sun is currently burning, or fusing, hydrogen to helium. After the hydrogen in the star’s core is exhausted, the star can burn helium to form progressively heavier elements, carbon and oxygen and so on, until iron and nickel are formed. Supernova explosions result when the cores of massive stars have exhausted their fuel supplies and burned everything into iron and nickel. Credit: NASA

Trace elements in stars may influence the evolution of habitable zones around them where life as we know it might dwell, scientists now find.

Stars are made nearly entirely from hydrogen and helium gas. Still, traces of heavier elements — which astronomers call metals, even if they are not what one normally think of as metals — can be found in stars as well, either inherited from the remains of older stars or forged via nuclear fusion.

Scientists can detect what elements a star possesses by looking at its light, which comes in a wide variety of wavelengths, some visible, many invisible. The wavelengths of light that matter emits often comes in specific clumps or lines, which can act like a fingerprint, revealing the identity of the material in question.

By looking at the wavelengths or spectra of light from nearby dwarf stars as part of searches for alien worlds, or exoplanets, researchers have with high precision determined the abundance of certain elements for more than a hundred of these stars, with more to come. Now researchers suggest variations in the compositions of these stars could impact the habitable zones around them.

Text and Images via Physorg. Continue HERE

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Ancient Astronomers Were No Fools

January 27, 2012

There’s no doubt ancient astronomers were clever folk. Realizing Earth was round, estimating the Sun’s distance, discovering heliocentricity — it’s quite a list. But Brad Schaefer (Louisiana State University) suggested at the recent American Astronomical Society meeting in Austin that we should add another light bulb to the glow shining from history: ancient astronomers may have corrected for dimming caused by the atmosphere, centuries before anyone came up with a physical model for it.

This dimming is called atmospheric extinction. Extinction happens because starlight has to pass through Earth’s atmosphere in order to reach us. But the effect isn’t uniform: if you spend time stargazing you’ve probably noticed that a star high up in the sky’s dome looks brighter than it does as it slides toward the horizon. That’s because light coming to us from near the horizon passes through more atmosphere than if it shines straight down from overhead. (The Sun looks redder at sunset and sunrise for the same reason.)

Astronomers have cataloged stars’ magnitudes for at least two millennia, all the way back to an ancient document called the Almagest. It was the Almagest that Schaefer began with — but his goal wasn’t to determine if astronomers in olden days accounted for extinction. He wanted to use the brightnesses reported in it to decide a long-standing debate over who wrote the catalog in the first place, Hipparchus of Rhodes (circa 150 BC) or Ptolemy of Alexandria (circa AD 150).

Written by Camille Carlisle, SKY & Telescope. Continue HERE

Image above: Frontispiece illustration from a Venetian 1496 edition of the Almagest, depicting Ptolemy instructing the 15th-century astronomer Regiomontanus (also known as Johannes Müller von Königsberg). Above the men is the zodiac, encircling the celestial sphere. Zachariel / Wikimedia Commons

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How to see the best meteor showers of 2012: Tools, tips and ‘save the dates’

January 2, 2012

Whether you’re watching from a downtown area or the dark countryside, here are some tips to help you enjoy these celestial shows of shooting stars. Those streaks of light are really caused by tiny specks of comet-stuff hitting Earth’s atmosphere at very high speed and disintegrating in flashes of light.

Major Meteor Showers (2012)

Quadrantids

Comet of Origin: 2003 EH1
Radiant: constellation Bootes
Active: Dec. 28, 2011-Jan. 12, 2012
Peak Activity: Jan. 4, 2012
Peak Activity Meteor Count: 120 meteors per hour
Meteor Velocity: 25.5 miles (41 kilometers) per second

Notes: A waxing gibbous moon will set at about 3 a.m. local time, allowing for several dark-sky hours of observing before dawn. This shower has a very sharp peak, usually only lasting a few hours, and is often obscured by winter weather. The alternate name for the Quadrantids is the Bootids. Constellation Quadrant Murales is now defunct, and the meteors appear to radiate from the modern constellation Bootes.

Lyrids

Comet of Origin: C/1861 G1 Thatcher
Radiant: constellation Lyra
Active: April 16-25, 2012
Peak Activity: April 21-22, 2012
Peak Activity Meteor Count: 10-20 meteors per hour
Meteor Velocity: 30 miles (49 kilometers) per second

Notes: A new moon on April 21 guarantees a dark sky in the late night and early morning hours, making this year ideal for observing from 10 p.m. to dawn. Lyrid meteors often produce luminous dust trains observable for several seconds.

Eta Aquarids

Comet of Origin: 1P Halley

Radiant: constellation Aquarius
Active: April 19-May 28, 2012
Peak Activity: May 5-6, 2012
Peak Activity Meteor Count: 10 meteors per hour
Meteor Velocity: 44 miles (66 kilometers) per second

Note: While the shower peaks an hour or two before dawn, the year’s closest and largest full moon will be out all night, resulting in a moonlit sky that will wash out all but the brightest meteors. Meteor watchers in the Southern Hemisphere stand the best chance of seeing any meteors.

Delta Aquarids

Comet of Origin: unknown, 96P Machholz suspected
Radiant: constellation Aquarius
Active: July 12-Aug. 23, 2012
Peak Activity: July 28-29, 2012
Peak Activity Meteor Count: Approximately 20 meteors per hour
Meteor Velocity: 25 miles (41 kilometers) per second

Notes: It’s not a good year for the Delta Aquarids — light from the August full moon make them nearly impossible to see.

Perseids

Comet of Origin: 109P/Swift-Tuttle
Radiant: constellation Perseus
Active: July 17-Aug. 24, 2012
Peak Activity: Aug. 12, 2012
Peak Activity Meteor Count: Approximately 100 meteors per hour
Meteor Velocity: 37 miles (59 kilometers) per second

Notes: Moonlight won’t be as big a problem as last year, as its waning crescent won’t rise until after midnight, and the shower peaks from about 10-11 p.m. local on the night of Aug. 12.

Orionids

Comet of Origin: 1P/Halley
Radiant: Just to the north of constellation Orion’s bright star Betelgeuse
Active: Oct. 2-Nov. 7, 2012
Peak Activity: Oct. 21, 2012
Peak Activity Meteor Count: Approximately 25 meteors per hour
Meteor Velocity: 41 miles (66 kilometers) per second

Note: With the second-fastest entry velocity of the annual meteor showers, meteors from the Orionids produce yellow and green colors and have been known to produce an odd fireball from time to time.

Leonids

Comet of Origin: 55P/Tempel-Tuttle
Radiant: constellation Leo
Active: Nov. 6-30, 2012
Peak Activity: Night of Nov. 17, 2012
Peak Activity Meteor Count: Approximately 15 per hour
Meteor Velocity: 44 miles (71 kilometers) per second

Note: The Leonids have not only produced some of the best meteor showers in history, but they have sometimes achieved the status of meteor storm. During a Leonid meteor storm, many thousands of meteors per hour can shoot across the sky. Scientists believe these storms recur in cycles of about 33 years, though the reason is unknown. The last documented Leonid meteor storm occurred in 2002.

Geminids

Comet of Origin: 3200 Phaethon
Radiant: constellation Gemini
Active: Dec. 4-17, 2012
Peak Activity: Dec. 13-14, 2012
Peak Activity Meteor Count: Approximately 120 meteors per hour
Meteor Velocity: 22 miles (35 kilometers) per second

Note: The Geminids are typically one of the best, and most reliable, of the annual meteor showers. This year’s peak falls perfectly with a new moon, guaranteeing a dark sky for the show in the nights on either side of the peak date. This shower is considered one of the best opportunities for younger viewers because the show gets going around 9 or 10 p.m.

Check tips at Physorg

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