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02-10-2021

The Coalsack Nebula

This stunning image captures a small region on the edge of the inky Coalsack Nebula, or Caldwell 99. Caldwell 99 is a dark nebula - a dense cloud of interstellar dust that completely blocks out visible wavelengths of light from objects behind it. The object at the center of the image is a (much smaller) protoplanetary nebula. The protoplanetary nebula phase is a late stage in the life of a star in which it has ejected a shell of hydrogen gas and is quickly heating up. This stage only lasts for a few thousand years before the protoplanetary nebula's central star reaches roughly 30,000 Kelvin (approximately 17,000 degrees Fahrenheit). At this point, the central star is producing enough energy to make its surrounding shell of gas glow, becoming what's known as a planetary nebula.

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02-14-2021

Long Stem Rosette Nebula

Would the Rosette Nebula by any other name look as sweet? The bland New General Catalog designation of NGC 2237 doesn't appear to diminish the appearance of this flowery emission nebula, at the top of the image, atop a long stem of glowing hydrogen gas. Inside the nebula lies an open cluster of bright young stars designated NGC 2244. These stars formed about four million years ago from the nebular material and their stellar winds are clearing a hole in the nebula's center, insulated by a layer of dust and hot gas. Ultraviolet light from the hot cluster stars causes the surrounding nebula to glow. The Rosette Nebula spans about 100 light-years across, lies about 5000 light-years away, and can be seen with a small telescope towards the constellation of the Unicorn (Monoceros).

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01-25-2021

The SpaceX Crew Dragon spaceship

iss064e025511 (Jan. 21, 2021) --- The SpaceX Crew Dragon spaceship, with its two lit crew windows, is pictured docked to the Harmony module's international docking adapter as the International Space Station orbited 264 miles above Swansea, Wales, in Great Britain.

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01-27-2021

Welding Underway on Orion for First Artemis Mission Landing Astronauts on the Moon

At NASA's Michoud Assembly Facility in New Orleans, technicians from Orion prime contractor Lockheed Martin have welded together three cone-shaped panels on Orion's crew module for the Artemis III mission that will land the first woman and next man on the Moon.

The crew module's primary structure, the pressure vessel, is comprised of seven machined aluminum alloy pieces that are welded together through a weld process that produces a strong, air-tight habitable space for astronauts during the mission. The pressure vessel is designed to withstand the harsh and demanding environment of deep space, and is the core structure upon which all the other elements of Orion's crew module are integrated. 

With welding complete on the crew module cone panels – one of which contains windows providing astronauts views of the Moon and Earth – work will begin joining the forward bulkhead to the tunnel to create the top of the spacecraft, followed by the barrel and aft bulkhead join to form the bottom of Orion.

Last, the forward bulkhead will be welded to the top of the panels and, for the seventh and closeout weld, the bottom of the cone panels will be joined to the barrel to complete the pressure vessel. Once welding of the Artemis III crew module primary structure is complete, it will be shipped to NASA's Kennedy Space Center in Florida where it will undergo further assembly beginning this fall.

Orion, the Space Launch System, and Exploration Ground Systems programs are foundational elements of the Artemis program. Artemis I will be the first integrated flight test of Orion and SLS and is targeted to launch later this year. Artemis II will follow and is the first crewed mission, taking humans farther into space than ever before.

Image credit: NASA/Michael DeMocker

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01-29-2021

Hubble Spots an Interstellar Interaction

The life of a planetary nebula is often chaotic, from the death of its parent star to the scattering of its contents far out into space. Captured here by the NASA/ESA Hubble Space Telescope, ESO 455-10 is one such planetary nebula, located in the constellation of Scorpius (The Scorpion). 

The oblate shells of ESO 455-10, previously held tightly together as layers of its central star, not only give this planetary nebula its unique appearance, but also offer information about the nebula. Seen in a field of stars, the distinct asymmetrical arc of material over the north side of the nebula is a clear sign of interactions between ESO 455-10 and the interstellar medium. 

The interstellar medium is the material such as diffuse gas between star systems and galaxies.  The star at the center of ESO 455-10 allows Hubble to see the interaction with the gas and dust of the nebula, the surrounding interstellar medium, and the light from the star itself. Planetary nebulae are thought to be crucial in galactic enrichment as they distribute their elements, particularly the heavier metal elements produced inside a star, into the interstellar medium which will in time form the next generation of stars. 

Text credit: European Space Agency (ESA)

Image credit: ESA/Hubble & NASA, L. Stanghellini

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The Dream Of String Theory Is An Unlikely Broken Box

“This is the dream of String Theory: that we can take this theory, like some enormous unbroken box, and stick the right key in it and watch it crumble away, leaving only a tiny piece left that perfectly describes our Universe. In the absence of such a key, String Theory can only be considered a physical speculation.

It may be interesting and promising, but until we can solve String Theory in a meaningful way to get the Universe we observe out of it, we have to admit to ourselves what String Theory truly is: a large, unbroken box that must somehow crumble in this particular, intricate fashion, to recover the Universe we observe. Until we understand how this occurs, String Theory will only remain a speculative dream.”

10 dimensions? Get rid of 6! Scalar-tensor theory of gravity? Get rid of the scalar part! Too much supersymmetry? Get rid of it! Too large of a Lie group? Get rid of everything we don’t observe! String theory has to throw away much, much more than it keeps if it wants to describe our Universe. 

Here’s the real dream of String Theory, and why it’s so hard to believe it will ever become a reality.

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Finding a New Earth

01-26-2021

Kepler-22b is the first planet discovered inside the habitable zone of a Sun-like star. This artist's conception from 2011, shows the first planet that NASA's Kepler mission has confirmed to orbit the region around a star where liquid water, a requirement for life on Earth, could exist. This exoplanet is 2.4 times the size of Earth, making it the smallest yet found to orbit in the middle of the habitable zone of a star like our Sun.

At the time scientists did not know if the planet has a predominantly rocky, gaseous or liquid composition. It's possible that the world would have clouds in its atmosphere, as depicted here in the artist's interpretation.

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01-18-2021

The Medulla Nebula Supernova Remnant

What powers this unusual nebula? CTB-1 is the expanding gas shell that was left when a massive star toward the constellation of Cassiopeia exploded about 10,000 years ago. The star likely detonated when it ran out of elements, near its core, that could create stabilizing pressure with nuclear fusion. The resulting supernova remnant, nicknamed the Medulla Nebula for its brain-like shape, still glows in visible light by the heat generated by its collision with confining interstellar gas. Why the nebula also glows in X-ray light, though, remains a mystery. One hypothesis holds that an energetic pulsar was co-created that powers the nebula with a fast outwardly moving wind. Following this lead, a pulsar has recently been found in radio waves that appears to have been expelled by the supernova explosion at over 1000 kilometers per second. Although the Medulla Nebula appears as large as a full moon, it is so faint that it took 130-hours of exposure with two small telescopes in New Mexico, USA, to create the featured image.

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Central NGC 1316: After Galaxies Collide via NASA https://ift.tt/2M2a0e4