When 13th-century Arab and Persian astronomers mapped the skies. Pair with this visual history of mapping the cosmos and 100 diagrams that changed the world.
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Alan Friedman - HD Photos of the Sun
Beautiful textures of our nearest star
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13 Must See Stargazing Events for 2013
Listed In Chronological Order
1) January 21 — Very Close Moon/Jupiter Conjunction
A waxing gibbous moon (78% illuminated) will pass within less than a degree to the south of Jupiter high in the evening sky. Your closed fist held out at arms length covers 10 degrees. These two wont get that close again until 2026.
2) February 2-23 — Best Evening View of Mercury
The planet Mercury will be far enough away from the glare of the Sun to be visible in the Western sky after sunset. It will be at its brightest on the 16th and dim quickly afterwards. On the 8th it will skim by the much dimmer planet Mars by about 0.4 degrees.
3) March 10-24 — Comet PANSTARRS at its best
First discovered in 2011, this comet should be coming back around for about 2 weeks. It will be visible low in the northwest sky after sunset. Here are some sources predicting what the comets may look like in the sky; 1, 2
4) April 25 — Partial Lunar Eclipse
A very minor, partial lunar eclipse (not visible in North America) where only about 2 percent of the moon’s diameter will be inside the dark shadow of the Earth.
5) May 9 — Annular Eclipse of the Sun (“Ring of Fire” Eclipse)
It will be visible in Northern Australia and parts of Papua New Guinea but mostly within the Pacific Ocean. See all the solar eclipse paths for 2001-2020 here.
6) May 24-30 — Dance of the Planets
Mercury, Venus and Jupiter will seemingly dance between each other in the twilight sky just after sunset as they will change their positions from one evening to the next. Venus will be the brightest of all, six times brighter than Jupiter.
7) June 23 — Biggest Full Moon of 2013
It will be the biggest full moon because the moon will be the closest to the Earth at this time making it a ‘supermoon’ and the tides will be affected as well creating exceptionally high and low tides for the next few days.
8) August 12 — Perseid Meteor Shower
One of the best and most reliable meteor showers of the year producing upwards of 90 meteors per hour provided the sky is dark. This year the moon won’t be in the way as much as it will set during the evening leaving the rest of the night dark. Here is a useful dark-sky finder tool.
9) October 18 — Penumbral Eclipse of the Moon
Visible mostly in Asia, Europe and Africa, at this time the 76% of the moon will be covered by the penumbral shadow of the Earth.
10) November 3 — Hybrid Eclipse of the Sun
A Hybrid Eclipse meaning, along its path, the eclipse will turn from Annular to Total and in this case most of the path will appear to be Total as there will be a slight ring of sunlight visible near the beginning of the track. This one will begin in the Atlantic (near the East Coast of the U.S.) and travel through Africa. See the path here. The greatest eclipse (with 100 seconds of totality) will appear in Liberia, near the West Coast of Africa.
11) Mid-November through December — Comet ISON
The second comet this year, ISON, could potentially be visible in broad daylight as it reaches its closest point to the Sun. It will reach that point on November 28 and it is close enough to the Sun to be categorized as a ‘Sungrazer’. Afterwards it will travel towards Earth (passing by within 40 million miles) a month later.
12) All of December — Dazzling Venus
The brightest planet of them all will shine a few hours after sundown in the Southwestern sky and for about 1.5 hours approaching New Years Eve. Around December 5th, a crescent moon will pass above the planet and the next night Venus will be at its brightest and wont be again until 2021.
13) December 13-14 — Geminid Meteor Shower
This is another great (if not the best) annual meteor shower. This year put on a show at about 120 meteors per hour and in 2013 it won’t be much different so expect another fantastic show. However, the moon - as it is a few days before full phase - will be in the way for most of the night obscuring some of the fainter meteors. You might have to stay up in the early morning hours (4am) to catch the all the meteors it has to offer. If you missed 2012’s Geminid Meteor Shower, here are some great photo-sets; 1, 2, 3
*The gif is of a total solar eclipse, from this video
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Today marks the 400th anniversary of an important milestone in astronomy: German astronomer Simon Marius viewed the Andromeda Galaxy through a telescope, the first time it was viewed through a telescope, which he described looking like a ‘candle shining through a horn.’ Andromeda is the nearest spiral galaxy to the Milky Way galaxy at 2.5 million light years away and has been the object of intense study since antiquity.
For his part, if Marius is ever remembered it is usually for his dispute with Galileo. In 1614 Marius described his discovery of the Jovian moons, pre-dating his discovery several days before Galileo’s date of discovery. Although the credit usually goes to Galileo, the names for the moons came from Marius:
Io, Europa, Ganimedes puer, atque Calisto
lascivo nimium perplacuere Iovi.
Io, Europa, the boy Ganymede, and Callisto greatly pleased lustful Jupiter.
Similarly, even though Messier credits Marius with the discovery of Andromeda as a galaxy, the Persian astronomer Abd al-Rhaman al-Sufi is now credited with the discovery over 600 years earlier!
Image of Andromeda courtesy NASA. Image of Marius in the public domain.
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Saturn’s B ring is spread out in all its glory in this image from Cassini. Scientists are trying to better understand the origin and nature of the various structures seen in the B ring.
Credit: NASA/JPL-Caltech/Space Science Institute
Saturn’s B ring is the densest and most massive of all the rings. The C ring is also visible inside the B ring and the A ring puts on an appearance beyond the Cassini Division near the top and bottom of the image.
This view looks toward the sunlit side of the rings from about 7 degrees above the ringplane. The image was taken in visible light with the Cassini spacecraft wide-angle camera on July 22, 2012.
The view was obtained at a distance of approximately 201,000 miles (324,000 kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 134 degrees. Image scale is 10 miles (16 kilometers) per pixel.
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This new global view of Earth’s city lights is a composite assembled from data acquired by the Suomi National Polar-orbiting Partnership (NPP) satellite.
Credit: NASA’s Earth Observatory/NOAA/DOD
The data was acquired over nine days in April 2012 and 13 days in October 2012. It took 312 orbits to get a clear shot of every parcel of Earth’s land surface and islands. This new data was then mapped over existing Blue Marble imagery of Earth to provide a realistic view of the planet.
The image was made possible by the satellite’s “day-night band” of the Visible Infrared Imaging Radiometer Suite, which detects light in a range of wavelengths from green to near-infrared and uses filtering techniques to observe dim signals such as city lights, gas flares, auroras, wildfires and reflected moonlight.
The day-night band observed Hurricane Sandy, illuminated by moonlight, making landfall over New Jersey on the evening of Oct. 29. Night images showed the widespread power outages that left millions in darkness in the wake of the storm.
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Sunset on the Alien Planet HD209458b: Osiris
The amazing image above of a sunset on exo-planet HD209458b 150 light years away, was reconstructed by Frederic Pont of the University of Exeter using data from a camera onboard the Hubble Space Telescope.
Pont used his knowledge of how the color of light changes based on chemicals it encounters, and computer modeling, to create an actual image of what a sunset on the actual planet would look like.
The large exo planet in question, exoplanet HD209458b, nicknamed Osiris, circles its star rather closely. At certain points, when the planet passes between us and its star, the light from that star passes through Osiris’s atmosphere before reaching us, which allowed Pont to determine the chemical composition of the atmosphere and deduce what colors would appear to the naked human eye.
The light from Osiris’s star is white, like our own sun, but when it passes through the sodium in Osirisi’s atmosphere, red light in it is absorbed, leaving the starlight to appear blue. But as the sun sets, the blue light is scattered in the same way as it is here on Earth (Rayleigh scattering) causing a gradual change to green, and then to a dim dark green. And finally, due to diffraction, the bottom of the image becomes slightly flattened.
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Source: dailygalaxy.com
The planet Uranus has 27 known moons, the first two of which (Titania and Oberon) were discovered by the man who discovered Uranus, Sir William Hershel, in 1787. Although Herschel believed he had seen as many as 6 moons and possibly a ring, nothing more was confirmed for another 50 years when the next two moons were discovered by William Lassell, which he named Ariel and Umbriel. Lassell deviated slightly from Herschel’s naming tradition and found Umbriel in Alexander Pope’s poem the Rape of the Lock. Since then all additional moons have been named for characters from either Shakespeare or Pope.
First, moons named after characters from Shakespeare:
- A Midsummer Night’s Dream: Titania, Oberon, Puck
- The Tempest: (Ariel), Miranda, Caliban, Sycorax, Prospero, Setebos, Stephano, Trinculo, Francisco, Ferdinand
- King Lear: Cordelia
- Hamlet: Ophelia
- The Taming of the Shrew: Bianca
- Troilus and Cressida: Cressida
- Othello: Desdemona
- Romeo and Juliet: Juliet, Mab
- The Merchant of Venice: Portia
- As You Like It: Rosalind
- Much Ado About Nothing: Margaret
- The Winter’s Tale: Perdita
- Timon of Athens: Cupid
Next, moons named from characters from Pope:
The Rape of the Lock (a poem by Alexander Pope):
- Ariel, Umbriel, Belinda
After the two moons discovered in the 1850s, another moon wasn’t discovered for another century, in 1948. The remaining almost two dozen moons were not discovered until the Voyager 2 flyby in 1986.
Learn more about the plays (including plots, characters and full texts) at www.shakespeare-online.com. You can find Alexander Pope at www.poemhunter.com. You can also click on any of the links above for links to wikipedia.
Image of Uranus’s moons to scale courtesy NASA, in the public domain.
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In case you haven’t already, check out 100,000 Stars, an interactive 3D visualization of our stellar neighbourhood. It’s a Google Chrome Experiment that draws on data from sources such as NASA and the European Space Agency to plot the stars closest to our own, helping you visualise our place in the galaxy. You can take a tour, or wander on your own. Happy exploration!
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Badass Scientist of the Week: Dr. Carl Sagan
Carl Sagan (1934–1996) was an astronomer, a skeptic, a science communicator and—to many—a poet. As a child he was fascinated with the stars, and this deep sense of wonder at the universe never abated all throughout his adult life. He studied at the University of Chicago, achieving his doctorate in astronomy and astrophysics by 1960, and over the next ten years, he held teaching and research posts at various universities and observatories. In 1970, he became director of Cornell University’s Laboratory for Planetary Studies and the David Duncan Professor of Astronomy and Space Sciences. At the same time, he played a leading role as a consultant at NASA, briefing the Apollo astronauts and being closely associated with unmanned planetary missions too, most notably the Mariner, Viking, Voyager, and Galileo expeditions. His research transformed planetary science, helping to solve mysteries such as the high temperatures of Venus, the seasonal changes of Mars and the reddish haze of Titan, and he also was a pioneer of the study of extraterrestrial life—but Carl is best known as a science communicator. In his award-winning books and his enormously popular 1980 TV series Cosmos, he captured the hearts and minds of millions with his easy charisma, his ability to explain difficult concepts, and his infectious wonder for the universe. His insights about our fragile world live on today as his legacy, and the way he continues to change the public’s perception of science is perhaps his greatest achievement—showing us that examining our universe using natural curiosity and the tools of science is a joyous, awe-inspiring endeavour. Happy birthday, Carl, and thank you for everything you’ve given us.
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Vulcan: The Hypothetical Planet
ercury has a curiously eccentric orbit that early astronomers had difficulty plotting. Although the Sun has the biggest gravitational influence on it, every other object in the Universe has an influence on it too according to Newton’s laws of gravitation. These are faint in comparison to the Sun’s enormous pull, but astronomers still have to factor them into calculations of Mercury’s motions. But in the mid 1800s, after painstaking calculation involving every known factor, French astronomer Urbain Jean Joseph Leverrier found that something was still unaccounted for. Neptune had just been discovered and had solved the problems with Uranus’s orbit, so rather than question Newton, Leverrier proposed in 1860 that there must be an object inside of Mercury’s orbit—a new planet that would account for irregularities. Leverrier called it Vulcan, but there was one problem: no one had ever observed it. Over the following decades, reports trickled in about various objects inside Mercury’s orbits, some perhaps small planets and others perhaps groups of asteroids. But the data didn’t match up, and no solid, consistent evidence could be provided. Controversy sprung up in the astronomical community, and yet, if Newton was correct, then there had to be another force acting on Mercury. In 1915, Einstein’s Theory of General Relativity explained it. It turns out that Newtonian gravity breaks down under extreme conditions, and relativity can step in to make corrections. Being so close to the enormous force of the Sun is certainly an extreme condition—basically, the Sun’s massive energy acts as the extra force on Mercury. When Einstein explained Mercury’s motions without the need for Vulcan, this shadow of a planet shrunk into non-existence—but it wasn’t a terrible hypothesis. Leverrier simply made the best inference he could with the available data.
Read More: The Planet that Wasn’t by Isaac Asimov
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The Science of Halloween: ‘Lunacy’ and the Full Moon
The Moon takes approximately 28 days to orbit the Earth, and it appears to goes through phases as it moves in relation to the light of the sun. Folk wisdom says that people act crazier than usual during a full Moon, and indeed the word “lunacy” is actually derived from the latin word for Moon, Luna. People claim that at full moons, not only do werewolves come out to play, but also depression, suicides, stabbings, traffic accidents and criminal activity rates rise. Surveys have found that over a third of the US population believe that the phase of the Moon affects human behaviour, and this percentage is even higher among mental health professionals (eighty!). But opinion counts for nothing when 99 percent of the evidence points the opposite way. Thousands of studies over the last half-century have looked into this issue, and although occasionally some have shown a correlation between phases and human behaviour, thorough follow-ups always disprove it. The main theory for why the Moon would affect humans is its grativational pull: it has an enormous effect on the tides, and since humans are about 80% water, it’s been suggested that the Moon must have a “biological-tide” effect on us too. This is doesn’t hold water at all, because the amount of water inside of us is so tiny compared to the oceans that a mosquito sitting on our arm literally exerts a more powerful gravitational pull on us than the Moon. But there is a more plausible theory that could explain the origin of this myth: a full moon means more light. The night is 250 times brighter with a full moon than no moon at all, so in times when there were no artificial lights, people would likely stay up later when there was a full moon. If more people are out, then clearly there’s a far greater chance of mischief and things going wrong.
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Earth-like Planet detected in our Neighbourhood
Alpha Centauri system is made up of three stars: a red dwarf named Proxima, and two stars very much like our own sun, imaginatively named Alpha Centauri A and B. It’s already famed in sci-fi, but just recently astronomers have discovered something that will make any space-lover swoon: a planet orbiting Alpha Centauri B. This exoplanet is 1.13 times the mass of Earth, but that’s where the similarities end: while Earth orbits at a distance of 150 million kilometres from its sun, “Alpha Centauri Bb” orbits in a scorching hot zone just six million kilometres from its star—its surface could even be covered with molten rock. The planet is definitely not in the Goldilock’s Zone, so it does not contain liquid water and therefore is unlikely to harbour life as we know it. Still, it’s an amazing discovery for several reasons. The method with which the planet was detected is groundbreaking: planets don’t orbit a stationary star, but in fact the planet and star orbit a common centre of gravity, which means the star moves in miniscule amounts. Alpha Centauri B constantly wobbles as the planet orbits around it and exerts a gravitational tug, but this wobble is tiny—no more than 1.8 k/ph—so for us to detect it is phenomenal. More than 450 observations were made over four years in order to be sure, and the discovery marks the highest precision ever achieved using this method of detection. Even more exciting is the fact that Alpha Centauri Bb it’s the closest known exoplanet to Earth, at only 4.3 lightyears away. In cosmic terms, that’s just next door. Statistically, low-mass planets are formed in multi-planetary systems, so its mere existence suggests that Alpha Centauri holds even more undiscovered planets—and perhaps some formed in habitable zones.
(Artist’s Impressions Credit: 1, 2)
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Like A Falling Apple
Formulated in 1687, Newton’s Law of Universal Gravitation was a turning point in physic. While the legend of the apple falling on his head is an exaggeration of the truth, Newton did have a brilliant insight: that every object in the universe attracts every other object. The force of attraction between two objects depends on only two things: the mass of the objects, and the distance between them. So, more massive objects exert a stronger force, while more distant objects exert a weaker force. Newton was able to formulate a simple equation to describe this, pictured above: force is equal to Newton’s gravitational constant, multiplied by masses of the objects, then divided by the square of the distance between the objects. What’s remarkable is that the law truly is universal—not only can it predict how things move here on Earth, but it can also the movements of the moon, planets, stars and even galaxies millions of lightyears away. Newton believed that the movement of every object in our universe could be predicted, but we know now that while his theory generally holds true, it is not precise. Einstein’s theory of general relativity had to step in to fill the holes.
(Image Credit: The Wonders Collection)
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A Spongey Rubble Pile
With an average diameter of 270 kilometres, the Saturn moon Hyperion is the largest irregular satellite in our solar system—and one of the strangest too. Until 1981, the moon just looked like a speck to astronomers, but the Voyager II flyby revealed its ungainly shape, its heavily pockmarked surface, and the way it spins in a tumbling, chaotic orbit around the ringed giant Saturn. More recently, the Cassini spacecraft has given us more in-depth images, revealing its porous spongey appearance (40% of the moon may just be empty space) and showing that the walls of its craters are bright, suggesting that the moon is composed mostly of water ice. Mysteriously, the floors of the craters are covered in dark reddish material. Data tells us that it may be organic and rich in complex hydrocarbons, which are sometimes the building blocks of life. It’s suspected that this material came from another of Saturn’s moons, Iapetus. The moon is made up of smaller ice and rock bodies, and is likely a remnant from a larger moon destroyed by a major collision—now, it doesn’t have enough gravity to actually compact itself, so it’s basically just an eccentric pile of rubble.
(Image Credit: National Geographic)
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