Astronomy picture of the day - 2017 September 13 - NGC 6334: The Cat's Paw Nebula

NGC 6334: The Cat's Paw Nebula 
Image Credit & Copyright: George Varouhakis

Explanation: Nebulas are perhaps as famous for being identified with familiar shapes as perhaps cats are for getting into trouble. Still, no known cat could have created the vast Cat's Paw Nebula visible in Scorpius. At 5,500 light years distant, Cat's Paw is an emission nebula with a red color that originates from an abundance of ionized hydrogen atoms. Alternatively known as the Bear Claw Nebula or NGC 6334, stars nearly ten times the mass of our Sun have been born there in only the past few million years. Pictured here is a deep field image of the Cat's Paw Nebula in light emitted by hydrogen, oxygen, and sulfur.

Astronomy picture of the day - 2017 September 12 - A Total Solar Eclipse Close-Up in Real Time

A Total Solar Eclipse Close-Up in Real Time
Video Credit & Copyright: Jun Ho Oh (KAIST, HuboLab);
Music: Flowing Air by Mattia Vlad Morleo

Explanation: How would you feel if the Sun disappeared? Many eclipse watchers across the USA surprised themselves with the awe that they felt and the exclamations that they made as the Sun momentarily disappeared behind the Moon. Perhaps expecting just a brief moment of dusk, the spectacle of unusually rapid darkness, breathtakingly bright glowing beads around the Moon's edge, shockingly pink solar prominences, and a strangely detailed coronastretching across the sky caught many a curmudgeon by surprise. Many of these attributes were captured in the featured real-time, three-minute video of last month's total solar eclipse. The video frames were acquired in Warm Springs,Oregon with equipment specifically designed by Jun Ho Oh to track a close-up of the Sun's periphery during eclipse. As the video ends, the Sun is seen being reborn on the other side of the Moon from where it departed.

Imagens - Porto - Portugal (2)

O Porto foi eleito o melhor destino europeu de 2017, ficando à frente de Milão e de Gdansk, no pódio das três cidades mais votadas

Foto Pedro Granadeiro/global Imagens

Astronomy picture of the day - 2011 September 11 - X-Rays Indicate Star Ripped Up by Black Hole

X-Rays Indicate Star Ripped Up by Black Hole 
Illustration Credit: M. Weiss, CXC, NASA

Explanation: What could rip a star apart? A black hole. Giant black holes in just the right mass range would pull on the front of a closely passing star much more strongly than on the back. Such a strong tidal force would stretch out a star and likely cause some of the star's gasses to fall into the black hole. The infalling gas has been predicted to emit just the same blast of X-rays that have recently been seen in the center of galaxy RX J1242-11. Above, an artist's illustration depicts the sequence of destruction (assuming that image-distorting gravitational-lens effects of the black hole are somehow turned off). Most of the stellar remains would be flung out into the galaxy. Such events are rare, occurring perhaps only one in 10,000 years for typical black holes at the center of typical galaxies.

Astronomy picture of the day - 2017 September 10 - Swirling Around the Eye of Hurricane Irma

Swirling Around the Eye of Hurricane Irma 
Video Credit: NASA, GOES-16 Satellite, SPoRT

Explanation: Why does a hurricane have an eye at its center? No one is yet sure. What happens in and around a hurricane's eye is well documented, though. Warm air rises around the eye's edges, cools, swirls, and spreads out over the large storm, sinking primarily at the far edges. Inside the low-pressure eye, air also sinks and warms -- which causes evaporation, calm, and clearing -- sunlight might even stream through. Just at the eye's edge is a towering eyewall, the area of the highest winds. It is particularly dangerous to go outside when the tranquil eye passes over because you are soon to experience, again, the storm's violent eyewall. Featured is one of the most dramatic videos yet taken of an eye and rotating eyewall. The time-lapse video was taken from space by NASA's GOES-16 satellite last week over one of the most powerful tropical cyclones in recorded history: Hurricane Irma. Hurricanes can beextremely dangerous and their perils are not confined to the storm's center.

Astronomy picture of the day - 2017 September 9 - Calm Waters and Geomagnetic Storm

Calm Waters and Geomagnetic Storm 
Image Credit & Copyright: Chris Cook

Explanation: Very recognizable stars of the northern sky are a backdrop for calm waters in this moonlit sea and skyscape off Cape Cod, Massachusetts. Taken on September 7, the photo also records a colorful display of northern lights or aurora borealis triggered by a severe geomagnetic storm. Visible crossing the Sun, the giant solar active region responsible, AR 2673, is much larger than planet Earth. It has produced the strongest flare of the current solar cycle and and the Earth-directed coronal mass ejection in the last few days.

Imagens - Porto - Portugal

O Porto foi eleito o melhor destino europeu de 2017, ficando à frente de Milão e de Gdansk, no pódio das três cidades mais votadas

Foto Leonel De Castro/global Imagens

Astronomy picture of the day - 2017 September 8 - The Great Gig in the Sky

The Great Gig in the Sky 
Image Credit & Copyright: Rogelio Bernal Andreo (Deep Sky Colors)

Explanation: There were no crowds on the beach at Phillips Lake, Oregon on August 21. But a few had come there to stand, for a moment, in the dark shadow of the Moon. From the beach, this unscripted mosaic photo records their much anticipated solar eclipse. In two vertical panels it catches the last few seconds of totality and the first instant of 3rd contact, just as the eclipse ends and sunlight faintly returns. Across the US those gathered along the path of totality also took pictures and shared their moment. And like those at Phillips Lake they may treasure the experience more than any planned or unplanned photograph of the total eclipse of the Sun.

Astronomy picture of the day - 2017 September 7 - The Flash Spectrum of the Sun

The Flash Spectrum of the Sun 
Image Credit & Copyright: Yujing Qin (University of Arizona)

Explanation: In clear Madras, Oregon skies, this colorful eclipse composite captured the elusive chromospheric or flash spectrum of the Sun. Only three exposures, made on August 21 with telephoto lens and diffraction grating, are aligned in the frame. Directly imaged at the far left, the Sun's diamond ring-like appearance at the beginning and end of totality brackets a silhouette of the lunar disk at maximum eclipse. Spread by the diffraction grating into the spectrum of colors toward the right, the Sun's photospheric spectrum traces the two continuous streaks. They correspond to the diamond ring glimpses of the Sun's normally overwhelming disk. But individual eclipse images also appear at each wavelength of light emitted by atoms along the thin, fleeting arcs of the solar chromosphere. The brightest images, or strongest chromospheric emission, are due to Hydrogen atoms. Red hydrogen alpha emission is at the far right with blue and purple hydrogen series emission to the left. In between, the brightest yellow emission is caused by atoms of Helium, an element only first discovered in the flash spectrum of the Sun.

Astronomy picture of the day - 2017 September 6 - The Climber and the Eclipse

The Climber and the Eclipse 
Image Credit & Copyright: Andrew Struder

Explanation: What should you do if your rock climbing picture is photobombed by a total eclipse of the Sun? Rejoice -- because your planning paid off. After months of considering different venues, and a week of scouting different locations in Oregon's Smith Rock State Park, a group of photographers and rock climbers led by Ted Hesser, Martina Tibell, and Michael Shainblum settled on picturesque 100-meter tall Monkey Face tower as the dramatic foreground for their images of the pending total solar eclipse. Tension mounted as the eclipse time approached, planned juxtapositions were scrutinized, and the placement of rock climber Tommy Smith was adjusted. Right on schedule, though, the Moon moved in front of the Sun, and Smith moved in front of the Moon, just as planned. The solar eclipse image displayed here actually shows a diamond ring, an eclipse phase when a bit of the distant Sun is still visible beyond the Moon's surface.