A cidade vista do Cristo Redentor
2014-12-19
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2014-12-18
Astronomy picture of the day - 18-12-2014 - NGC 7331 and Beyond
Image Credit & Copyright: Tony Hallas
Explanation: Big, beautiful spiral galaxy NGC 7331 is often touted as an analog to our own Milky Way. About 50 million light-years distant in the northern constellation Pegasus, NGC 7331 was recognized early on as a spiral nebulaand is actually one of the brighter galaxies not included in Charles Messier's famous 18th century catalog. Since the galaxy's disk is inclined to our line-of-sight, long telescopic exposures often result in an image that evokes a strong sense of depth. The effect is further enhanced in this sharp image from a small telescope by galaxies that lie beyond the gorgeous island universe. The most prominent background galaxies are about one tenth the apparent size of NGC 7331 and so lie roughly ten times farther away. Their close alignment on the sky with NGC 7331 occurs just by chance. Seen through faint foreground dust clouds lingering above the plane of Milky Way, this visual grouping of galaxies is known as the Deer Lick Group.
2014-12-17
Astronomy picture of the day - 17-12-2014 - Geminid Fireball over Mount Balang
Image Credit: Alvin Wu
Explanation: This was a sky to remember. While viewing the Geminids meteor shower a few days ago, a bright fireball was captured over Mt. Balang, China with particularly picturesque surroundings. In the foreground, a sea of light clouds slowly floated between dark mountain peaks. In the background, the constellation of Orion shone brightly, with the familiar three stars of Orion's belt visible near the image top right. Sirius, the brightest star in the night sky, is visible near the image center. The bright fireball flashed for only a fraction of second on the lower right. The source of the fireball was a pebble that intersected the protective atmosphere of Earth, originally expelled by the Sun-orbiting asteroid-like object 3200 Phaethon.
2014-12-16
Imagens do Mundo - Paris - France
Instalación de una pista de patinaje en el hall central del Grand Palais en París (Francia).
Astronomy picture of the day - 16-12-2014 - W5: Pillars of Star Formation
Image Credit: WISE, IRSA, NASA; Processing & Copyright : Francesco Antonucci
Explanation: How do stars form? Images of the star forming region W5 like those in the infrared by NASA's Wide Field Infrared Survey Explorer (WISE) satellite provide clear clues with indications that massive stars near the center of empty cavities are older than stars near the edges. A likely reason for this is that the older stars in the center are actually triggering the formation of the younger edge stars. The triggered star formation occurs when hot outflowing gas compresses cooler gas into knots dense enough to gravitationally contract into stars. In the featured scientifically-colored infrared image, spectacular pillars, left slowly evaporating from the hot outflowing gas, provide further visual clues.W5 is also known as IC 1848, and together with IC 1805 form a complex region of star formation popularly dubbed the Heart and Soul Nebulas. The above image highlights a part of W5 spanning about 2,000 light years that is rich instar forming pillars. W5 lies about 6,500 light years away toward the constellation of Cassiopeia.
2014-12-15
Astronomy picture of the day - 15-12-2014 - The Potsdam Gravity Potato
Image Credit: CHAMP, GRACE, GFZ, NASA, DLR
Explanation: Why do some places on Earth have higher gravity than others? Sometimes the reason is unknown. To help better understand the Earth's surface, sensitive measurments by the orbiting satellites GRACE and CHAMPwere used to create a map of Earth's gravitational field. Since a center for studying this data is in Potsdam, Germany, and since the result makes the Earth look somewhat like a potato, the resulting geoid has been referred to as the Potsdam Gravity Potato. High areas on this map, colored red, indicate areas where gravity is slightly stronger than usual, while in blue areas gravity is slightly weaker. Many bumps and valleys on the Potsdam Gravity Potato can be attributed to surface features, such as the North Mid-Atlantic Ridge and the Himalayan Mountains, but others cannot, and so might relate to unusually high or low sub-surface densities. Maps like this also help calibrate changes in the Earth's surface including variable ocean currents and the melting of glaciers. The above map was made in 2005, but more recent and more sensitive gravity maps of Earth was produced in 2011.
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