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Rescooped by Philippe Trebaul from Amazing Science
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Distant Black Hole Spins at Half the Speed of Light

Distant Black Hole Spins at Half the Speed of Light | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Back when the universe was half its present age, supermassive black holes were feeding from a steady and plentiful diet of neighboring galaxies, the first measurement of a distant supermassive black hole’s spin shows.


Taking advantage of a naturally occurring zoom lens in space, astronomers analyzed X-rays streaming from near the mouth of a supermassive black hole powering a quasar about 6 billion light years from Earth.


“The ‘lens’ galaxy acts like a natural telescope, magnifying the light from the faraway quasar,” University of Michigan astronomer Rubens Reis explains in a paper published in this week’s Nature.


Analyzing four magnified images created by the lens galaxy -- an elliptical galaxy about 3 billion light years away -- Reis and colleagues found that the quasar’s black hole is spinning at half the speed of light.


The spin rate directly relates to how black holes feed and grow: The steadier the diet, the faster the spin, computer models show. “If the mass accretion was more messy it would suggest that the black hole would have a lower spin,” astronomer Mark Reynolds, also with University of Michigan, told Discovery News.


“What we found in this system is that it’s spinning very rapidly,” Reynolds said, consuming mass equivalent to about one sun per year. Spin rates may evolve over time, reflecting changes in evolution of galaxies.


At some distance, the black holes’ spins might be even higher, approaching light speed, and then slow down to RX J1131’s spin rate.


“If we go back further, maybe they’ll all be maximally spinning because of more mergers and more things happening. Or maybe they’ll be less spinning. We can theoretically produce both scenarios at the moment,” Reynolds said.



Via Dr. Stefan Gruenwald
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Rescooped by Philippe Trebaul from iGeneration - 21st Century Education (Pedagogy & Digital Innovation)
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Curriki - Best Free Apps for Space and Astronomy

Curriki - Best Free Apps for Space and Astronomy | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Curriki resource: More than 40 years after the first moon landing, we're still impressed by that ʺgiant leap for mankind.ʺ To honor this achievement, we've pulled together 5 of the best free apps related to astronomy.

Via Tom D'Amico (@TDOttawa)
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Richard Krause's curator insight, July 7, 2013 11:18 PM

Great site for resources

Janet Price's curator insight, September 24, 2013 11:30 PM

Some excellent apps to use! free

 

Joe Liu's curator insight, October 23, 2013 8:00 PM

This site can be used to have students download free apps that would be relevant for understanding and increasing the curiosity for the Space topic. I have already downloaded two of the apps which I found to engage the class as a whole.  They can use the apps as resources to complete assessments on phases of the moon, to support their own observations.

 

The best aspect is the free access. This means even more students can have access to this resource. However, it would be great if this site was updated more regularly with new apps when they become available.

Rescooped by Philippe Trebaul from Science News
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[VIDEO] Astronomy - Basics of the Sun

ASTRONOMY: http://www.scoop.it/t/science-news?tag=astronomy

 


Via Sakis Koukouvis
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11 Most Amazing Astronomy Stories of 2011 | Alien Planets, Dark Energy, Solar Flares & Pluto's Moons | Asteroids & Planetary Science | Space.com

11 Most Amazing Astronomy Stories of 2011 | Alien Planets, Dark Energy, Solar Flares & Pluto's Moons | Asteroids & Planetary Science | Space.com | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
From potentially habitable alien planets to dark energy to a new moon around Pluto, here are the 11 best astronomy stories of 2011.

Via Sakis Koukouvis
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Incredible high-resolution video of Jupiter | Bad Astronomy | Discover Magazine

Incredible high-resolution video of Jupiter | Bad Astronomy | Discover Magazine | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Astronomy | Jupiter | The Pic du Midi observatory in France is renowned for its very stable atmospheric conditions, allowing high resolution pictures to be taken.

Via Sakis Koukouvis
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Huge solar flare slams into Earth - Astronomy Magazine

Huge solar flare slams into Earth - Astronomy Magazine | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Astronomy.com is for anyone who wants to learn more about astronomy events, cosmology, planets, galaxies, asteroids, astrophotography, the Big Bang, black holes, comets, constellations, eclipses, exoplanets, nebulae, meteors, quasars, observing,...

Via Sakis Koukouvis
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Amazing Science: Astronomy Postings

Amazing Science: Astronomy Postings | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it

Astronomy is one of the oldest natural sciences and studies celestial objects (such as moons, planets, stars, nebulae, and galaxies), the physics, chemistry, mathematics, and evolution of such objects, and phenomena that originate outside the atmosphere of Earth, including supernovae explosions, gamma ray bursts, and cosmic background radiation. Theoretical astronomy is oriented towards the development of computer or analytical models to describe celestrial phenomena. A related but distinct subject, cosmology, is concerned with studying the universe as a whole.


Via Dr. Stefan Gruenwald
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Astronomy Essentials: What is the Zodiac and how does time influences it?

Astronomy Essentials: What is the Zodiac and how does time influences it? | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it

The Zodiac is defined by 12 constellations that lie along the annual path of the sun across the sky. These 12 signs listed in a horoscope, are closely tied to how the Earth moves through the heavens. The signs are derived from 12 constellations that mark out the path on which the sun appears to travel over the course of a year. In principle, dates in a horoscope should correspond to when the sun passes through each constellation. But they don’t, much of the time. And a closer examination of the motion of the Earth, the sun, and the stars shows the Zodiac to be more complex than you might imagine!

 

As the Earth orbits the sun, the sun appears to pass in front of different constellations. Much like the moon appears in a slightly different place in the sky each night, the location of the sun relative to distant background stars drifts in an easterly direction from day to day. It’s not that the sun is actually moving. The motion is entirely an illusion caused by the Earth’s own motion around our star.

 

As the earth orbits the sun, the sun appears to move against the background stars (red line). The constellations (green) through which the sun passes define the zodiac. Over the course of a year, the sun appears to be in front of, or “in”, different constellations. One month, the sun appears in Gemini; the next month, in Cancer. The dates listed in the newspaper’s horoscope identify when the sun appears in a particular astrological sign. For example, March 21 through April 19 are set aside for the sign Aries. But your astrological sign doesn’t necessarily tell you what constellation the sun was in on the day you were born. If only it were that simple!

 

To understand why constellations no longer align with their corresponding signs, we need to know a little bit more about how the Earth moves. And something about how we measure time. Time is a fiendishly difficult thing to define, especially if we insist on using the sun and stars as a reference. Our calendar is, for better or worse, tied to the seasons. June 21—the summer solstice above the equator and the winter solstice below—marks the day the sun appears at its most northerly point in the sky. At the June solstice, the North Pole is most tilted towards the sun.

What makes this complicated is that the North Pole is not always pointing in the same direction relative to the backdrop stars. Our planet spins like a top. And like a top, the Earth also wobbles! A wobbling Earth makes the North Pole trace out a circle on the celestial sphere. Now, the wobble is quite slow—it takes 26,000 years to wobble around once—but as the years go by, the effect accumulates.

 

Tidal forces from the sun cause the earth’s axis to wobble over a 26,000 year period. The wobble changes where in Earth’s orbit the solstices and equinoxes occur. Over the course of one orbit around the sun, the direction of the Earth’s axis drifts ever so slightly. This means that where along our orbit the solstice occurs also changes by a very small amount. The solstice actually occurs about 20 minutes earlier than one full trip in front of the backdrop stars!

 

Since we tie our calendar (and astrologers tie the signs) to the solstices and equinoxes, the Earth does not actually complete an entire orbit in one year. The seasonal or tropical year is actually a hair less time than one full orbit (sidereal year). This means that, each year, where the sun is relative to the stars on any given day—June 21, for example—drifts a very tiny amount.

But wait about 2000 years, and the sun will be sitting in an entirely different constellation!

On the June solstice 2000 years ago, the sun was sitting almost halfway between Gemini and Cancer. On this year’s June solstice, the sun will be sitting between Gemini and Taurus. In the year 4609, the June solstice point will pass out of the constellation Taurus and into the constellation Aries.

 

The signs more or less aligned with their corresponding constellations when the modern Western Zodiac was defined about 2,000 years ago. But in the intervening centuries, the slow wobble of the Earth’s axis has caused the solstice and equinox points to shift roughly 30o westward relative to the constellations! At present, signs and constellations are about one calendar month off. In another two thousand years or so, they’ll be about two months off.


Via Sakis Koukouvis, Dr. Stefan Gruenwald
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Want astronomy apps? There's a catalog for that

Want astronomy apps? There's a catalog for that | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
With the plethora of mobile apps now available for astronomy applications, its hard to keep track of them all.

Via Sakis Koukouvis
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Epic tantrum thrown by 30 octillion ton baby | Bad Astronomy | Discover Magazine

Epic tantrum thrown by 30 octillion ton baby | Bad Astronomy | Discover Magazine | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Astronomy | bipolar nebula | So you saw my gallery yesterday of gorgeous pictures from 2011, right?

Via Sakis Koukouvis
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A hidden world revealed: Titan | Bad Astronomy | Discover Magazine

A hidden world revealed: Titan | Bad Astronomy | Discover Magazine | JOIN SCOOP.IT AND FOLLOW ME ON SCOOP.IT | Scoop.it
Astronomy | Cassini | We've sent space probes to every planet in our solar system (and if you're a die-hard Pluto fan, you only have to wait 4 more years).

Via Sakis Koukouvis
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