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Look Up! Perseid Meteor Shower Peaks Aug. 11-12

Asteroid Watch logo. Aug. 2, 2016 Make plans now to stay up late or set the alarm early next week to see a cosmic display of “shooting stars” light up the night sky. Known for it’s fast and bright meteors, the annual Perseid meteor shower is anticipated to be one of the best potential meteor viewing opportunities this year. The Perseids show up every year in August when Earth ventures through trails of debris left behind by an ancient comet. This year, Earth may be in for a closer encounter than usual with the comet trails that result in meteor shower, setting the stage for a spectacular display.

Image above: An outburst of Perseid meteors lights up the sky in August 2009 in this time-lapse image. Stargazers expect a similar outburst during next week’s Perseid meteor shower, which will be visible overnight on Aug. 11 and 12. Image Credits: NASA/JPL. “Forecasters are predicting a Perseid outburst this year with double normal rates on the night of Aug. 11-12,” said Bill Cooke with NASA’s Meteoroid Environments Office in Huntsville, Alabama. “Under perfect conditions, rates could soar to 200 meteors per hour.” An outburst is a meteor shower with more meteors than usual. The last Perseid outburst occurred in 2009. Every Perseid meteor is a tiny piece of the comet Swift-Tuttle, which orbits the sun every 133 years. Each swing through the inner solar system can leave trillions of small particles in its wake. When Earth crosses paths with Swift-Tuttle’s debris, specks of comet-stuff hit Earth’s atmosphere and disintegrate in flashes of light. These meteors are called Perseids because they seem to fly out of the constellation Perseus. Most years, Earth might graze the edge of Swift-Tuttle’s debris stream, where there’s less activity. Occasionally, though, Jupiter’s gravity tugs the huge network of dust trails closer, and Earth plows through closer to the middle, where there’s more material. This may be one of those years. Experts at NASA and elsewhere agree that three or more streams are on a collision course with Earth. “Here’s something to think about. The meteors you’ll see this year are from comet flybys that occurred hundreds if not thousands of years ago,” said Cooke. “And they’ve traveled billions of miles before their kamikaze run into Earth’s atmosphere.” How to Watch the Perseids The best way to see the Perseids is to go outside between midnight and dawn on the morning of Aug. 12. Allow about 45 minutes for your eyes to adjust to the dark. Lie on your back and look straight up. Increased activity may also be seen on Aug. 12-13. For stargazers experiencing cloudy or light-polluted skies, a live broadcast of the Perseid meteor shower will be available via Ustream overnight on Aug. 11-12 and Aug. 13-14, beginning at 10 p.m. EDT.: http://www.ustream.tv/channel/nasa-msfc

Meteor Moment: Viewing Tips.

More about the Perseids Perseid meteors travel at the blistering speed of 132,000 miles per hour (59 kilometers per second). That’s 500 times faster than the fastest car in the world. At that speed, even a smidgen of dust makes a vivid streak of light when it collides with Earth’s atmosphere. Peak temperatures can reach anywhere from 3,000 to 10,000 degrees Fahrenheit as they speed across the sky. The Perseids pose no danger to Earth. Most burn up 50 miles above our planet. But an outburst could mean trouble for spacecraft. About the Meteoroid Environment Office It’s Cooke’s job to help NASA understand and prepare for risks posed by meteoroids. He leads a team of meteor experts in the Meteoroid Environments Office at NASA’s Marshall Space Flight Center. They study meteoroids in space so that NASA can protect our nation’s satellites, spacecraft and even astronauts aboard the International Space Station from these bits of tiny space debris. Related links: Meteors & Meteorites: http://www.nasa.gov/topics/solarsystem/features/watchtheskies/index.html Meteoroid Environments Office: https://www.nasa.gov/offices/meo/home/index.html Image (mentioned), Video, Text, Credits: NASA/Jennifer Harbaugh. Greetings, Orbiter.ch Full article

Space Infographicsby Nick Wiinikka

prints/poster/phone cases and more by the artist available here

Radar Observations of Asteroid 2014 HQ124

Radar data of asteroid 2014 HQ124 taken over for hours on June 8, 2014, when the asteroid was between 864.000 miles (1.39 million kilometers) and 902.00 miles (1,45 million kilometers) from Earth. The data reveals asteroid 2014 HQ124 to be an elongated, irregular object that is at least 1200 feet (370 meters) wide on it long axis. The radar was obtained using NASA’s 70 meters Goldstone antenna, the same antenna used for communicating with spacecraft in deep space. The Goldstone radar team paired with the Arecibo Observatory (Goldstone sending radar, Arecibo receiving) for the first five frames of this movie in order to collect higher quality data resulting in shaper images. The other frames were made by both sending and receiving with antennas at the Goldstone complex.

Credit: NASA/JPL

Galaxies: Types and morphology

A galaxy is a gravitationally bound system of stars, stellar remnants, interstellar gas, dust, and dark matter. Galaxies range in size from dwarfs with just a few hundred million (108) stars to giants with one hundred trillion (1014) stars, each orbiting its galaxy’s center of mass.

Galaxies come in three main types: ellipticals, spirals, and irregulars. A slightly more extensive description of galaxy types based on their appearance is given by the Hubble sequence. 

Since the Hubble sequence is entirely based upon visual morphological type (shape), it may miss certain important characteristics of galaxies such as star formation rate in starburst galaxies and activity in the cores of active galaxies.

Ellipticals

The Hubble classification system rates elliptical galaxies on the basis of their ellipticity, ranging from E0, being nearly spherical, up to E7, which is highly elongated. These galaxies have an ellipsoidal profile, giving them an elliptical appearance regardless of the viewing angle. Their appearance shows little structure and they typically have relatively little interstellar matter. Consequently, these galaxies also have a low portion of open clusters and a reduced rate of new star formation. Instead they are dominated by generally older, more evolved stars that are orbiting the common center of gravity in random directions.

Spirals

Spiral galaxies resemble spiraling pinwheels. Though the stars and other visible material contained in such a galaxy lie mostly on a plane, the majority of mass in spiral galaxies exists in a roughly spherical halo of dark matter that extends beyond the visible component, as demonstrated by the universal rotation curve concept.

Spiral galaxies consist of a rotating disk of stars and interstellar medium, along with a central bulge of generally older stars. Extending outward from the bulge are relatively bright arms. In the Hubble classification scheme, spiral galaxies are listed as type S, followed by a letter (a, b, or c) that indicates the degree of tightness of the spiral arms and the size of the central bulge.

Barred spiral galaxy

A majority of spiral galaxies, including our own Milky Way galaxy, have a linear, bar-shaped band of stars that extends outward to either side of the core, then merges into the spiral arm structure. In the Hubble classification scheme, these are designated by an SB, followed by a lower-case letter (a, b or c) that indicates the form of the spiral arms (in the same manner as the categorization of normal spiral galaxies). 

Ring galaxy

A ring galaxy is a galaxy with a circle-like appearance. Hoag’s Object, discovered by Art Hoag in 1950, is an example of a ring galaxy. The ring contains many massive, relatively young blue stars, which are extremely bright. The central region contains relatively little luminous matter. Some astronomers believe that ring galaxies are formed when a smaller galaxy passes through the center of a larger galaxy. Because most of a galaxy consists of empty space, this “collision” rarely results in any actual collisions between stars.

Lenticular galaxy

A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. They contain large-scale discs but they do not have large-scale spiral arms. Lenticular galaxies are disc galaxies that have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks.

Irregular galaxy

An irregular galaxy is a galaxy that does not have a distinct regular shape, unlike a spiral or an elliptical galaxy. Irregular galaxies do not fall into any of the regular classes of the Hubble sequence, and they are often chaotic in appearance, with neither a nuclear bulge nor any trace of spiral arm structure.

Dwarf galaxy

Despite the prominence of large elliptical and spiral galaxies, most galaxies in the Universe are dwarf galaxies. These galaxies are relatively small when compared with other galactic formations, being about one hundredth the size of the Milky Way, containing only a few billion stars. Ultra-compact dwarf galaxies have recently been discovered that are only 100 parsecs across.

Interacting

Interactions between galaxies are relatively frequent, and they can play an important role in galactic evolution. Near misses between galaxies result in warping distortions due to tidal interactions, and may cause some exchange of gas and dust. Collisions occur when two galaxies pass directly through each other and have sufficient relative momentum not to merge.

Starburst

Stars are created within galaxies from a reserve of cold gas that forms into giant molecular clouds. Some galaxies have been observed to form stars at an exceptional rate, which is known as a starburst. If they continue to do so, then they would consume their reserve of gas in a time span less than the lifespan of the galaxy. Hence starburst activity usually lasts for only about ten million years, a relatively brief period in the history of a galaxy.

Active galaxy

A portion of the observable galaxies are classified as active galaxies if the galaxy contains an active galactic nucleus (AGN). A significant portion of the total energy output from the galaxy is emitted by the active galactic nucleus, instead of the stars, dust and interstellar medium of the galaxy.

The standard model for an active galactic nucleus is based upon an accretion disc that forms around a supermassive black hole (SMBH) at the core region of the galaxy. The radiation from an active galactic nucleus results from the gravitational energy of matter as it falls toward the black hole from the disc. In about 10% of these galaxies, a diametrically opposed pair of energetic jets ejects particles from the galaxy core at velocities close to the speed of light. The mechanism for producing these jets is not well understood.

The main known types are: Seyfert galaxies, quasars, Blazars, LINERS and Radio galaxy.

source

images: NASA/ESA, Hubble (via wikipedia)

sich wie die Axt im Wald benehmen

to behave like the axe in the forest

to behave like a bull in the china shop

(via thatswhywelovegermany)

The latest from Brock Davis - love his work! 

The Great Nebula in Carina : In one of the brightest parts of Milky Way lies a nebula where some of the oddest things occur. NGC 3372, known as the Great Nebula in Carina, is home to massive stars and changing nebulas. The Keyhole Nebula , the bright structure just above the image center, houses several of these massive stars and has itself changed its appearance. The entire Carina Nebula spans over 300 light years and lies about 7,500 light-years away in the constellation of Carina. Eta Carinae, the most energetic star in the nebula, was one of the brightest stars in the sky in the 1830s, but then faded dramatically. Eta Carinae is the brightest star near the image center, just left of the Keyhole Nebula. While Eta Carinae itself maybe on the verge of a supernova explosion, X-ray images indicate that much of the Great Carina Nebula has been a veritable supernova factory. via NASA

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