Η διαστημική φωτογραφία της ημέρας - Αρχείο

[Sleepy]

δεν μπορω να καταλαβω τι ακριβως ειναι...μπορειτε σαν μεγαλυτερα...βρεφη να μου εξηγησετε?

[Xenios]

Αρχική Δημοσίευση από Sleepy δεν μπορω να καταλαβω τι ακριβως ειναι...μπορειτε σαν μεγαλυτερα...βρεφη να μου εξηγησετε?

Ένα πουλάκι μου είπε ότι ξέρεις Αγγλικά :-)
Είναι μια ανάλυση ενός μέρους των δακτυλίων του Κρόνου σε μεγάλη ανάλυση. Το βλέπουμε σαν γραμμούλες λόγω της μεγάλης ταχύτητας των σωματιδίων που αποτελούν τον δακτύλιο.

[Xenios]

Αρχική Δημοσίευση από Gildor Πως τους ηρθε να ονομασουν τον εξωτερικο δακτυλιο F, απορια θα το εχω

Οι δακτύλιοι έχουν αρίθμηση από τον μεγαλύτερο στον μικρότερο Α Β C D E F G H I K κοκ.

Αν είχατε την υπομονή να διαβάστε το κείμενο, θα το βλέπατα. RTFM θα πω τώρα :-)

[Xenios]

Apogee Moon, Perigee Moon
Credit & Copyright: Anthony Ayiomamitis

Explanation: Tonight, those blessed with clear skies can enjoy a glorious Full Moon, (exact full phase at 0452 UT, October 26). In fact, the Moon will reach its full phase within a few hours of perigee, the closest point in its elliptical orbit, making it the largest Full Moon of 2007. On April 3, the Full Moon was within hours of apogee, the farthest point in the lunar orbit, corresponding to the smallest Full Moon of 2007. The difference in apparent size between the largest and smallest Full Moon is quite dramatic and similar to this side by side comparison of the lunar apogee/perigee apparitions from 2006. But seen in the sky many months apart, the change is difficult to notice. Skygazers should also enjoy the Moon on Saturday, October 27, as it encounters the lovely Pleiades star cluster. Because the Moon will be so bright, it will be easiest to spot the Pleiades stars near the Moon with binoculars or a small telescope.

Tomorrow's picture: Comet Holmes in outburst

Πηγή

[Xenios]

Comet Holmes in Outburst
Credit & Copyright: Babak Tafreshi and (inset) Alan Friedman

Explanation: Comet 17P/Holmes stunned comet watchers across planet Earth earlier this week. On October 24, it increased in brightness over half a million times in a matter of hours. The outburst transformed it from an obscure and faint comet quietly orbiting the Sun with a period of about 7 years to a naked-eye comet rivaling the brighter stars in the constellation Perseus. Recorded on that date, this view from Tehran, Iran highlights the comet's (enhanced and circled) dramatic new visibility in urban skies. The inset (left) is a telescopic image from a backyard in Buffalo, New York showing the comet's greatly expanded coma, but apparent lack of a tail. Holmes' outburst could be due to a sudden exposure of fresh cometary ice or even the breakup of the comet nucleus. The comet may well remain bright in the coming days.

Tomorrow's picture: Carina the Great

Πηγή

[Xenios]

The Great Carina Nebula
Credit & Copyright: Robert Gendler and Stephane Guisard

Explanation: A jewel of the southern sky, the Great Carina Nebula, aka NGC 3372, spans over 300 light-years, one of our galaxy's largest star forming regions. Like the smaller, more northerly Orion Nebula, the Carina Nebula is easily visible to the naked eye, though at a distance of 7,500 light-years it is some 5 times farther away. This stunning telescopic view reveals remarkable details of the region's glowing filaments of interstellar gas and dark cosmic dust clouds. The Carina Nebula is home to young, extremely massive stars, including the still enigmatic variable Eta Carinae, a star with well over 100 times the mass of the Sun. Eta Carinae is the bright star left of the central dark notch in this field and just below the dusty Keyhole Nebula (NGC 3324).

Tomorrow's picture: cloudy sky

Πηγή

[Xenios]

Noctilucent Clouds Over Sweden
Credit & Copyright: P-M Hedén

Explanation: Sometimes it's night on the ground but day in the air. As the Earth rotates to eclipse the Sun, sunset rises up from the ground. Therefore, at sunset on the ground, sunlight still shines on clouds above. Under usual circumstances, a pretty sunset might be visible, but unusual noctilucent clouds float so high up they can be seen well after dark. Pictured above last month, a network of noctilucent clouds cast a colorful but eerie glow after dusk near Vallentuna, Sweden. Although noctilucent clouds are thought to be composed of small ice-coated particles, much remains unknown about them. Satellites launched to help study these clouds includes Sweden's Odin and NASA's AIM. Recent evidence indicates that at least some noctilucent clouds result from freezing water exhaust from Space Shuttles.

Tomorrow's picture: exploding comet

Πηγή

[Xenios]

A Telescopic View of Erupting Comet Holmes
Credit & Copyright: Igor Chekalin

Explanation: What's happened to Comet Holmes? A normally docile comet discovered over 100 years ago, Comet 17P/Holmes suddenly became nearly one million times brighter last week, possibly over just a few hours. In astronomical terms, the comet brightened from magnitude 17, only visible through a good telescope, to magnitude 3, becoming visible with the unaided eye. Comet Holmes had already passed its closest to the Sun in 2007 May outside the orbit of Mars and was heading back out near Jupiter's orbit when the outburst occurred. The comet's sudden brightening is likely due to some sort of sunlight-reflecting outgassing event, possibly related to ice melting over a gas-filled cavern, or possibly even a partial breakup of the comet's nucleus. Pictured above through a small telescope last Thursday, Comet Holmes appeared as a fuzzy yellow spot, significantly larger in angular size than Earth-atmosphere blurred distant stars. Although Comet Holmes' orbit will place it in northern hemisphere skies for the next two years, whether it will best be viewed through a telescope or sunglasses remains unknown.

Tomorrow's picture: in the heart of the heart

Πηγή

[Xenios]

Comet Holmes' Coma Expands
Credit & Copyright: Eric Allen Observatoire du Cégep de Trois-Rivières

Explanation: Go outside tonight and see Comet Holmes. No binoculars or telescopes are needed -- just curiosity and a sky map. Last week, Comet 17P/Holmes underwent an unusual outburst that vaulted it unexpectedly from obscurity into one of the brightest comets in recent years. Sky enthusiasts from the northern hemisphere have been following the comet's progress closely. Pictured above Quebec, Canada, the coma of Comet Holmes has been noticeably expanding over the past few days. In the above picture, an image of Jupiter has been placed artificially nearby to allow for a comparison of angular sizes. Jupiter has been scaled to the size it would appear at the current location of Comet Holmes. How Comet Holmes will further evolve is unknown, with one possibility being that the expanding gas cloud that started from its recent outburst will slowly disperse and fade.

Tomorrow's picture: astronomical holiday

Πηγή

[Xenios]

Κάντε κλικ για μεγέθυνση

Halloween and the Ghost Head Nebula
Credit: Mohammad Heydari-Malayeri (Observatoire de Paris) et al., ESA, NASA

Explanation: Halloween's origin is ancient and astronomical. Since the fifth century BC, Halloween has been celebrated as a cross-quarter day, a day halfway between an equinox (equal day / equal night) and a solstice (minimum day / maximum night in the northern hemisphere). With our modern calendar, however, the real cross-quarter day will occur next week. Another cross-quarter day is Groundhog's Day. Halloween's modern celebration retains historic roots in dressing to scare away the spirits of the dead. Perhaps a fitting modern tribute to this ancient holiday is the above-pictured Ghost Head Nebula taken with the Hubble Space Telescope. Appearing similar to the icon of a fictional ghost, NGC 2080 is actually a star forming region in the Large Magellanic Cloud, a satellite galaxy of our own Milky Way Galaxy. The Ghost Head Nebula spans about 50 light-years and is shown in representative colors.

Tomorrow's picture: peculiar galaxies

Πηγή

[Xenios]

Κάντε κλικ για να δείτε σε μεγάλη ανάλυση την μοναδική αυτή φωτογραφία

Peculiar Arp 87
Credit: NASA, ESA, and the Hubble Heritage Team (STScI / AURA)

Explanation: A cosmic bridge of stars, gas, and dust stretches for over 75,000 light-years and joins this peculiar pair of galaxies cataloged as Arp 87. The bridge is strong evidence that these two immense star systems have passed close to each other and experienced violent tides induced by mutual gravity. As further evidence, the face-on spiral galaxy on the right, also known as NGC 3808A, exhibits many young blue star clusters produced in a burst of star formation. The twisted edge-on spiral on the left (NGC 3808B) seems to be wrapped in the material bridging the galaxies and surrounded by a curious polar ring. While such interactions are drawn out over billions of years, repeated close passages should ultimately result in the merger of this pair of galaxies into a larger single galaxy of stars. Although this scenario does look peculiar, galactic mergers are thought to be common, with Arp 87 representing a stage in this inevitable process. The Arp 87 pair are about 300 million light-years distant toward the constellation Leo. The prominent edge-on spiral at the far left appears to be a more distant background galaxy and not involved in the on-going merger.

Tomorrow's picture: three nebulae

Πηγή

[Xenios]

Three Nebulae in Narrow Band
Credit & Copyright: Michael Mayda

Explanation: Narrow band filters and a false-color palette give these three nebulae a stunning appearance against the cosmic canvas of the central Milky Way. All three are stellar nurseries about 5,000 light-years or so distant, toward the nebula rich constellation Sagittarius. In the 18th century, astronomer Charles Messier cataloged two of them; colorful M8, above and right of center, and compact M20 at the left. The third, NGC 6559, is at bottom right. Over a hundred light-years across, M8 is also known as the Lagoon Nebula. Divided by obscuring dust lanes, M20's popular moniker is the Trifid. In the composite image, narrow emission lines from sulfur, hydrogen, and oxygen atoms recorded through the filters, are mapped into broader red, green, and blue colors respectively. The color scheme was made popular in Hubble Space Telescope images. But for ground-based telescopes, narrow band filters also make it possible to reject overwhelming light-pollution and capture compelling images of the cosmos from urban skies.

Tomorrow's picture: another look

Πηγή

[Xenios]

Golden Comet Holmes
Credit & Copyright: Don Goldman

Explanation: Surprising Comet Holmes remains easily visible as a round, fuzzy cloud in the northern constellation Perseus. Skywatchers with telescopes, binoculars, or those that just decide to look up can enjoy the solar system's latest prodigy as it glides about 150 million kilometers from Earth, beyond the orbit of Mars. Still expanding, Holmes now appears to be about 1/3 the size of the Full Moon, and many observers report a yellowish tint to the dusty coma. A golden color does dominate this telescopic view recorded on November 1, showing variations across the coma's bright central region. But where's the comet's tail? Like any good comet, Holmes' tail would tend to point away from the Sun. That direction is nearly along our line-of-sight behind the comet, making its tail very difficult to see.

Tomorrow's picture: Sunday's child

Πηγή

[Xenios]

The Closest Galaxy: Canis Major Dwarf
Illustration Credit & Copyright: R. Ibata (Strasbourg Observatory, ULP) et al., 2MASS, NASA

Explanation: What is the closest galaxy to the Milky Way? The new answer to this old question is the Canis Major dwarf galaxy. For many years astronomers thought the Large Magellan Cloud (LMC) was closest, but its title was supplanted in 1994 by the Sagittarius dwarf galaxy. Recent measurements indicate that the Canis Major dwarf is only 42,000 light years from the Galactic center, about three quarters of the distance to the Sagittarius dwarf and a quarter of the distance to the LMC. The discovery was made in data from the 2MASS-sky survey, where infrared light allows a better view through our optically opaque Galactic plane. The labeled illustration above shows the location of the newly discovered Canis Major dwarf and its associated tidal stream of material in relation to our Milky Way Galaxy. The Canis Major dwarf and other satellite galaxies are slowly being gravitationally ripped apart as they travel around and through our Galaxy.

Tomorrow's picture: green comet

Πηγή

[Xenios]

Comet Holmes Grows a Tail
Credit & Copyright: Vicent Peris and José Luis Lamadrid (astrofoto.es)

Explanation: Comet Holmes continues to be an impressive sight to the unaided eye. The comet has diminished in brightness only slightly, and now clearly appears to have a larger angular extent than stars and planets. Astrophotographers have also noted a distinctly green appearance to the comet's coma over the past week. Pictured above over Spain in three digitally combined exposures, Comet 17P/Holmes now clearly sports a tail. The blue ion tail is created by the solar wind impacting ions in the coma of Comet Holmes and pushing them away from the Sun. Comet Holmes underwent an unexpected and dramatic increase in brightness starting only two weeks ago. The detail visible in Comet Holmes' tail indicates that the explosion of dust and gas that created this dramatic brightness increase is in an ongoing and complex event. Comet Holmes will move only slightly on the sky over during the next month.

Tomorrow's picture: sun explosion

Πηγή