Sunday, October 8, 2017

Dark Molecular Cloud Barnard

Where did all the stars go? What used to be considered a hole in the sky is now known to astronomers as a dark molecular cloud. Here, a high concentration of dust and molecular gasabsorb practically all the visible light emitted from background stars. The eerily dark surroundings help make the interiors ofmolecular clouds some of the coldest and mostisolated places in the universe. One of the most notable of these dark absorption nebulae is a cloud toward the constellation Ophiuchusknown as Barnard 68pictured here. That no stars are visible in the center indicates thatBarnard 68 is relatively nearby, with measurements placing it about 500 light-years away and half a light-year across. It is not known exactly how molecular clouds likeBarnard 68 form, but it is known that these clouds are themselves likely places for new stars to form. In fact, Barnard 68 itself has been found likely to collapse and form a new star system. It is possible to look right through the cloud in infrared light.
Image Credit: FORS Team8.2-meter VLT Antu,ESO

Thursday, October 5, 2017

Pluto's Bladed Terrain

Imaged during the New Horizons spacecraft flyby in July 2015, Pluto's bladed terrain is captured in this close-up of the distant world.The bizarre texture belongs to fields of skyscraper-sized, jagged landforms made almost entirely of methane ice, found at extreme altitudes near Pluto's equator. Casting dramatic shadows, the tall, knife-like ridges seem to have been formed by sublimation. By that process, condensed methane ice turns directly to methane gas without passing through a liquid phase during Pluto's warmer geological periods. On planet Earth, sublimation can also produce standing fields of knife-like ice sheets, found along the high plateau of the Andes mountain range. Known as penitentes, those bladed structures are made of water ice and at most a few meters tall.

New Horizons

Wednesday, October 4, 2017

95 Minutes Over Jupiter

This sequence of color-enhanced images shows how quickly the viewing geometry changes for NASA’s Juno spacecraft as it swoops by Jupiter. The images were obtained by JunoCam.

Once every 53 days, Juno swings close to Jupiter, speeding over its clouds. In just two hours, the spacecraft travels from a perch over Jupiter’s north pole through its closest approach (perijove), then passes over the south pole on its way back out. This sequence shows 11 color-enhanced images from Perijove 8 (Sept. 1, 2017) with the south pole on the left (11th image in the sequence) and the north pole on the right (first image in the sequence).

The first image on the right shows a half-lit globe of Jupiter, with the north pole approximately at the upper center of the image close to the terminator -- the dividing line between night and day. As the spacecraft gets closer to Jupiter, the horizon moves in and the range of visible latitudes shrinks. The second and third images in this sequence show the north polar region rotating away from the spacecraft's field of view while the first of Jupiter's lighter-colored bands comes into view. The fourth through the eighth images display a blue-colored vortex in the mid-southern latitudes near Points of Interest "Collision of Colours," "Sharp Edge," "Caltech, by Halka," and "Structure01." The Points of Interest are locations in Jupiter’s atmosphere that were identified and named by members of the general public. Additionally, a darker, dynamic band can be seen just south of the vortex. In the ninth and tenth images, the south polar region rotates into view. The final image on the left displays Jupiter's south pole in the center.

From the start of this sequence of images to the end, roughly 1 hour and 35 minutes elapsed.

JunoCam's raw images are available for the public to peruse and process into image products at:

www.missionjuno.swri.edu/junocam      

Image Credits: NASA/JPL-Caltech/SwRI/MSSS/Kevin M. Gill

Larger view

Juno