The Keyhole in the Carina Nebula : The dark dusty Keyhole Nebula gets its name from its unusual shape. The looping Keyhole, in this featured classic image by the Hubble Space Telescope, is a smaller region inside the larger Carina Nebula. Dramatic dark dust knots and complex features are sculpted by the winds and radiation of the Carina Nebula’s many massive and energetic stars. In particular, the shape of the dust cloud on the upper left of the Keyhole Nebula may stimulate the human imagination to appear similar to, for example, a superhero flying through a cloud, arm up, with a saved person in tow below. The region lies about 7,500 light-years away in planet Earth’s southern sky. The Keyhole Nebula was created by the dying star Eta Carina , out of the frame, which is prone to violent outbursts during its final centuries. via NASA
In case you didn’t know, NASA has some serious sciart game when it comes to their mission posters. This is just a fraction of the full galleries for both Shuttle and Space Station missions. I love how all the astronauts are clearly so into this.
This dazzling image shows the globular cluster Messier 69, or M 69 for short, as viewed through the NASA/ESA Hubble Space Telescope. Globular clusters are dense collections of old stars. In this picture, foreground stars look big and golden when set against the backdrop of the thousands of white, silvery stars that make up M 69.
Another aspect of M 69 lends itself to the bejewelled metaphor: As globular clusters go, M 69 is one of the most metal-rich on record. In astronomy, the term “metal” has a specialised meaning: it refers to any element heavier than the two most common elements in our Universe, hydrogen and helium. The nuclear fusion that powers stars created all of the metallic elements in nature, from the calcium in our bones to the carbon in diamonds. Successive generations of stars have built up the metallic abundances we see today.
Because the stars in globular clusters are ancient, their metallic abundances are much lower than more recently formed stars, such as the Sun. Studying the makeup of stars in globular clusters like M 69 has helped astronomers trace back the evolution of the cosmos.
M 69 is located 29 700 light-years away in the constellation Sagittarius (the Archer). The famed French comet hunter Charles Messier added M 69 to his catalogue in 1780. It is also known as NGC 6637.
The image is a combination of exposures taken in visible and near-infrared light by Hubble’s Advanced Camera for Surveys, and covers a field of view of approximately 3.4 by 3.4 arcminutes.
NASA Sparks Interest in Enigmatic Earthworks of Kazakhstan
Archaeologists call them the Nazca lines of Kazakhstan – hundreds of giant geoglyphs formed with earthen mounds and timber found stretched across the landscape in northern Kazakhstan. They are designed in a variety of geometric shapes, including crosses, squares, rings, and even a swastika, a prehistoric symbol that has been in use for at least 12,000 years. Now NASA is helping to piece together this ancient landscape by using space-age technology to reveal more of the colossal earthworks, recognizable only from the air.
Pluto’s ‘heart’ sheds light on a possible buried ocean
Ever since NASA’s New Horizons spacecraft flew by Pluto last year, evidence has been mounting that the dwarf planet may have a liquid ocean beneath its icy shell. Now, by modeling the impact dynamics that created a massive crater on Pluto’s surface, a team of researchers has made a new estimate of how thick that liquid layer might be.
The study, led by Brown University geologist Brandon Johnson and published in Geophysical Research Letters, finds a high likelihood that there’s more than 100 kilometers of liquid water beneath Pluto’s surface. The research also offers a clue about the composition of that ocean, suggesting that it likely has a salt content similar to that of the Dead Sea.
“Thermal models of Pluto’s interior and tectonic evidence found on the surface suggest that an ocean may exist, but it’s not easy to infer its size or anything else about it,” said Johnson, who is an assistant professor in Brown’s Department of Earth, Environmental and Planetary Sciences. “We’ve been able to put some constraints on its thickness and get some clues about composition.”
The research focused on Sputnik Planum, a basin 900 kilometers across that makes up the western lobe the famous heart-shaped feature revealed during the New Horizons flyby. The basin appears to have been created by an impact, likely by an object 200 kilometers across or larger.
The story of how the basin relates to Pluto’s putative ocean starts with its position on the planet relative to Pluto’s largest moon, Charon. Pluto and Charon are tidally locked with each other, meaning they always show each other the same face as they rotate. Sputnik Planum sits directly on the tidal axis linking the two worlds. That position suggests that the basin has what’s called a positive mass anomaly — it has more mass than average for Pluto’s icy crust. As Charon’s gravity pulls on Pluto, it would pull proportionally more on areas of higher mass, which would tilt the planet until Sputnik Planum became aligned with the tidal axis.
But a positive mass anomaly would make Sputnik Planum a bit of an odd duck as craters go.
“An impact crater is basically a hole in the ground,” Johnson said. “You’re taking a bunch of material and blasting it out, so you expect it to have negative mass anomaly, but that’s not what we see with Sputnik Planum. That got people thinking about how you could get this positive mass anomaly.”
Part of the answer is that, after it formed, the basin has been partially filled in by nitrogen ice. That ice layer adds some mass to the basin, but it isn’t thick enough on its own to make Sputnik Planum have positive mass, Johnson says.
The rest of that mass may be generated by a liquid lurking beneath the surface.
Like a bowling ball dropped on a trampoline, a large impact creates a dent on a planet’s surface, followed by a rebound. That rebound pulls material upward from deep in the planet’s interior. If that upwelled material is denser than what was blasted away by the impact, the crater ends up with the same mass as it had before the impact happened. This is a phenomenon geologists refer to as isostatic compensation.
Water is denser than ice. So if there were a layer of liquid water beneath Pluto’s ice shell, it may have welled up following the Sputnik Planum impact, evening out the crater’s mass. If the basin started out with neutral mass, then the nitrogen layer deposited later would be enough to create a positive mass anomaly.
“This scenario requires a liquid ocean,” Johnson said. “We wanted to run computer models of the impact to see if this is something that would actually happen. What we found is that the production of a positive mass anomaly is actually quite sensitive to how thick the ocean layer is. It’s also sensitive to how salty the ocean is, because the salt content affects the density of the water.”
The models simulated the impact of an object large enough to create a basin of Sputnik Planum’s size hitting Pluto at a speed expected for that part in the solar system. The simulation assumed various thicknesses of the water layer beneath the crust, from no water at all to a layer 200 kilometers thick.
The scenario that best reconstructed Sputnik Planum’s observed size depth, while also producing a crater with compensated mass, was one in which Pluto has an ocean layer more than 100 kilometers thick, with a salinity of around 30 percent.
“What this tells us is that if Sputnik Planum is indeed a positive mass anomaly —and it appears as though it is — this ocean layer of at least 100 kilometers has to be there,” Johnson said. “It’s pretty amazing to me that you have this body so far out in the solar system that still may have liquid water.”
As researchers continue to look at the data sent by New Horizons, Johnson is hopeful that a clearer picture of Pluto’s possible ocean will emerge.
Johnson’s co-authors on the paper were Timothy Bowling of the University of Chicago and Alexander Trowbridge and Andrew Freed from Purdue University.
Terra eclipsa o Sol durante a viagem de volta da missão Apollo 12.
The Earth eclipses the Sun during the trip back of Apollo 12 mission.
#nasa #retro #tbt #apollo12 #apollo #apollomission #tripbackhome #viagemdevolta #eclipse #sun #sol #earth #terra #astronomia #astronomy #astrogram #observatoriog1 #solarsunday #space #espaço #lua #moon
Consider this: You can see less than 1% of the electromagnetic spectrum and hear less than 1% of the acoustic spectrum. As you read this, you are traveling at 220 km/sec across the galaxy. 90% of the cells in your body carry their own microbial DNA and are not “you.” The atoms in your body are 99.9999999999999999% empty space and none of them are the ones you were born with, but they all originated in the belly of a star. Human beings have 46 chromosomes, 2 less than the common potato. The existence of the rainbow depends on the conical photo-receptors in your eyes; to animals without cones, the rainbow does not exist. So you don’t just look at a rainbow, you create it.