Archives de catégorie : Picture

NGC 4565: Galaxy on Edge

Magnificent spiral galaxy NGC 4565 is viewed edge-on from planet Earth. Also known as the Needle Galaxy for its narrow profile, bright NGC 4565 is a stop on many telescopic tours of the northern sky, in the faint but well-groomed constellation Coma Berenices. This sharp, colorful image reveals the galaxy’s bulging central core cut by obscuring dust lanes that lace NGC 4565’s thin galactic plane. An assortment of other background galaxies is included in the pretty field of view, with neighboring galaxy NGC 4562 at the upper right. NGC 4565 itself lies about 40 million light-years distant and spans some 100,000 light-years. Easily spotted with small telescopes, sky enthusiasts consider NGC 4565 to be a prominent celestial masterpiece Messier missed. via NASA https://ift.tt/2It0o9C

Reflections on vdB 9

Centered in a well-composed celestial still life, pretty, blue vdB 9 is the 9th object in Sidney van den Bergh’s 1966 catalog of reflection nebulae. It shares this telescopic field of view, about twice the size of a full moon on the sky, with stars and dark, obscuring dust clouds in the northerly constellation Cassiopeia. Cosmic dust is preferentially reflecting blue starlight from embedded, hot star SU Cassiopeiae, giving vdB 9 the characteristic bluish tint associated with a classical reflection nebula. SU Cas is a Cepheid variable star, though even at its brightest it is just too faint to be seen with the unaided eye. Still Cepheids play an important role in determining distances in our galaxy and beyond. At the star’s well-known distance of 1,540 light-years, this cosmic canvas would be about 24 light-years across. via NASA https://ift.tt/2TajiGo

Comet Iwamoto Before Spiral Galaxy NGC 2903

It isn’t every night that a comet passes a galaxy. Last Thursday, though, binocular comet C/2018 Y1 (Iwamoto) moved nearly in front of a spiral galaxy of approximately the same brightness: NGC 2903. Comet Iwamoto was discovered late last year and orbits the Sun in a long ellipse. It last visited the inner Solar System during the Middle Ages, around the year 648. The comet reached its closest point to the Sun — between Earth and Mars — on February 6, and its closest point to Earth a few days ago, on February 13. The featured time-lapse video condenses almost three hours into about ten seconds, and was captured last week from Switzerland. At that time Comet Iwamoto, sporting a green coma, was about 10 light minutes distant, while spiral galaxy NGC 2903 remained about 30 million light years away. Two satellites zip diagonally through the field about a third of the way through the video. Typically, a few comets each year become as bright as Comet Iwamoto. via NASA https://go.nasa.gov/2Egfnjp

Dragon Aurora over Iceland

Have you ever seen a dragon in the sky? Although real flying dragons don’t exist, a huge dragon-shaped aurora developed in the sky over Iceland earlier this month. The aurora was caused by a hole in the Sun’s corona that expelled charged particles into a solar wind that followed a changing interplanetary magnetic field to Earth’s magnetosphere. As some of those particles then struck Earth’s atmosphere, they excited atoms which subsequently emitted light: aurora. This iconic display was so enthralling that the photographer’s mother ran out to see it and was captured in the foreground. No sunspots have appeared on the Sun so far in February, making the multiple days of picturesque auroral activity this month somewhat surprising. via NASA https://go.nasa.gov/2V5BcHF

NGC 2359: Thor s Helmet

NGC 2359 is a helmet-shaped cosmic cloud with wing-like appendages popularly called Thor’s Helmet. Heroically sized even for a Norse god, Thor’s Helmet is about 30 light-years across. In fact, the helmet is more like an interstellar bubble, blown as a fast wind from the bright, massive star near the bubble’s center inflates a region within the surrounding molecular cloud. Known as a Wolf-Rayet star, the central star is an extremely hot giant thought to be in a brief, pre-supernova stage of evolution. NGC 2359 is located about 15,000 light-years away in the constellation Canis Major. The remarkably detailed image is a mixed cocktail of data from broadband and narrowband filters that captures natural looking stars and the glow of the nebula’s filamentary structures. It highlights a blue-green color from strong emission due to oxygen atoms in the glowing gas. via NASA https://go.nasa.gov/2toqgcs

Opportunity at Perseverance Valley

Opportunity had already reached Perseverance Valley by June of 2018. Its view is reconstructed in a colorized mosaic of images taken by the Mars Exploration Rover’s Navcam. In fact, Perseverance Valley is an appropriate name for the destination. Designed for a 90 day mission, Opportunity had traveled across Mars for over 5,000 sols (martian solar days) following a January 2004 landing in Eagle crater. Covering a total distance of over 45 kilometers (28 miles), its intrepid journey of exploration across the Martian landscape has come to a close here. On June 10, 2018, the last transmission from the solar-powered rover was received as a dust storm engulfed the Red Planet. Though the storm has subsided, eight months of attempts to contact Opportunity have not been successful and its trailblazing mission ended after almost 15 years of exploring the surface of Mars. via NASA https://go.nasa.gov/2SXYB0E

Solar System Family Portrait

On Valentine’s Day in 1990, cruising four billion miles from the Sun, the Voyager 1 spacecraft looked back one last time to make this first ever Solar System family portrait. The complete portrait is a 60 frame mosaic made from a vantage point 32 degrees above the ecliptic plane. In it, Voyager’s wide angle camera frames sweep through the inner Solar System at the left, linking up with gas giant Neptune, the Solar System’s outermost planet, at the far right. Positions for Venus, Earth, Jupiter, Saturn, Uranus, and Neptune are indicated by letters, while the Sun is the bright spot near the center of the circle of frames. The inset frames for each of the planets are from Voyager’s narrow field camera. Unseen in the portrait are Mercury, too close to the Sun to be detected, and Mars, unfortunately hidden by sunlight scattered in the camera’s optical system. Closer to the Sun than Neptune at the time, small, faint Pluto’s position was not covered. via NASA https://go.nasa.gov/2GFYEY9

The Helix Nebula in Hydrogen and Oxygen

Is the Helix Nebula looking at you? No, not in any biological sense, but it does look quite like an eye. The Helix Nebula is so named because it also appears that you are looking down the axis of a helix. In actuality, it is now understood to have a surprisingly complex geometry, including radial filaments and extended outer loops. The Helix Nebula (aka NGC 7293) is one of brightest and closest examples of a planetary nebula, a gas cloud created at the end of the life of a Sun-like star. The remnant central stellar core, destined to become a white dwarf star, glows in light so energetic it causes the previously expelled gas to fluoresce. The featured picture, taken in the light emitted by oxygen (shown in blue) and hydrogen (shown in red), was created from 74 hours of exposure over three months from a small telescope in a backyard of suburban Melbourne, Australia. A close-up of the inner edge of the Helix Nebula shows complex gas knots of unknown origin. via NASA https://go.nasa.gov/2tiiwZz

Plane Crossing a Crescent Moon

No, this is not a good way to get to the Moon. What is pictured is a chance superposition of an airplane and the Moon. The contrail would normally appear white, but the large volume of air toward the setting Sun preferentially knocks away blue light, giving the reflected trail a bright red hue. Far in the distance, well behind the plane, is a crescent Moon, also slightly reddened. Captured a month ago above Valais, Switzerland, the featured image was taken so soon after sunset that planes in the sky were still in sunlight, as were their contrails. Within minutes, unfortunately, the impromptu sky show ended. The plane crossed the Moon and moved out of sight. The Moon set. The contrail became unilluminated and then dispersed. via NASA https://go.nasa.gov/2tqTvM1

New Data: Ultima Thule Surprisingly Flat

Ultima Thule is not the object humanity thought that it was last month. When the robotic New Horizons spacecraft zoomed past the distant asteroid Ultima Thule (officially 2014 MU69) in early January, early images showed two circular lobes that when most simply extrapolated to 3D were thought to be, roughly, spheres. However, analyses of newly beamed-back images — including many taken soon after closest approach — shows eclipsed stars re-appearing sooner than expected. The only explanation possible is that this 30-km long Kuiper belt object has a different 3D shape than believed only a few weeks ago. Specifically, as shown in the featured illustration, it now appears that the larger lobe — Ultima — is more similar to a fluffy pancake than a sphere, while the smaller lobe — Thule — resembles a dented walnut. The remaining uncertainty in the outlines are shown by the dashed blue lines. The new shape information indicates that gravity — which contracts more massive bodies into spheres — played perhaps less of a role in contouring the lobes of Ultima Thule than previously thought. The New Horizons spacecraft continued on to Ultima Thule after passing Pluto in mid-2015. New data and images are still being received. via NASA https://go.nasa.gov/2THETDp