NASA Astronomy Picture of the Day 2016 May 25 

NGC 5078 and Friends 

This sharp telescopic field of view holds two bright galaxies. Barred spiral NGC 5101 (top right) and nearly edge-on system NGC 5078 are separated on the sky by about 0.5 degrees or about the apparent width of a full moon. Found within the boundaries of the serpentine constellation Hydra, both are estimated to be around 90 million light-years away and similar in size to our own large Milky Way galaxy. In fact, if they both lie at the same distance their projected separation would be only 800,000 light-years or so. That’s easily less than half the distance between the Milky Way and the Andromeda Galaxy.

NGC 5078 is interacting with a smaller companion galaxy, cataloged as IC 879, seen just left of the larger galaxy’s bright core. Even more distant background galaxies are scattered around the colorful field. Some are even visible right through the face-on disk of NGC 5101. But the prominent spiky stars are in the foreground, well within our own Milky Way.

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Scientists Find Evidence for Ninth Planet in Solar System

A planet larger than Earth could be hiding in the cold, dark depths of the solar system. The presence of the planet, which would lie far beyond Pluto, is betrayed by the curious orbits of a handful of distant icy worlds.

A ninth large planet may lurk deep in the outer solar system. The planet, illustrated here, is far from the sun and thought to be gaseous like Uranus and Neptune, though smaller than both ice giants.

As described Wednesday in the Astronomical Journal, the gravitational signature of a large, lurking planet is written into the peculiar orbits of these farflung worlds. Called extreme Kuiper Belt Objects, the misbehaving bodies trace odd circles around the sun that have puzzled scientists for years.

It’s tantalizing evidence that a ninth large planet might live in the solar system, though the world hasn’t been detected yet.

Read more at National Geographic

physics-astronomy.com
New Research Suggests That Time Runs Backwards Inside Black Holes

A new research paper published in Physical Review Letters has brought forward a significant new understanding of general relativity laws, and has found some strange physics taking place inside black holes. Specifically, that the direction of time could be reversed within them. 

Several physical procedures are perfectly symmetric in time. Take a pendulum for instance. If someone shows you a video of a pendulum swinging, you cannot differentiate if the video is actually moving forward or backward. But some processes are not symmetric at all. We can tell that a pendulum will ultimately slow because of friction and we know that it was triggered at some point, so we can give a temporal direction to physics. 

The directionality of time and our view of it was called the “Arrow of Time” by British astronomer Arthur Eddington, and it has been connected to the entropy of the cosmos.

(excerpt - click the link for the complete article)

anonymous asked:

So how many arms does our galaxy have? I see artist's impressions have 2, then scientists in 2013 suggesting 4. How is it so unclear? We can see galaxies hundreds of times further away and see their structure, why can't we determine the shape of our own backyard? Making a 3D map doesn't sound hard, all you need is the distance and direction of a percentage of every star in the galaxy, wouldn't our satellites have this information readily available? Thanks for your response in advanced! :)

Interesting that you bring this up because Phil Plait @badastronomy recently published over at @slateinbrief a piece in response to and rebuttal of the Tweetstorm of ignorance released into the social mediasphere by Ken Ham (yes, that Ham). 

Amidst this collection of face palm-inducing “gotcha” Tweets, Ken doll set Phil up to address the complexity of galactic evolution by sharing the below episode (#37) of Crash Course Astronomy where the Milky Way’s spiral arms are discussed in great detail. 

From Phil Plait: 

When you look at the spiral of cream in your coffee cup after you stir it, the inner part does spin faster than the outer parts. But galaxies aren’t like that. The arms aren’t coherent structures that spin like cream in your mug o’ java; they’re more like traveling traffic jams. By the way, scientists have known for nearly a century that spiral arms don’t and shouldn’t wind themselves up.

The way that Phil addresses people who disseminate bad science while having a voice and influence over others - especially in Ham’s case with his taking to the stage to “debate” Bill Nye on evolution, among other things - is quite humbling and inspiring to see during an age of information so widely accessible, searchable, and shareable that we choose not to thoroughly educate ourselves at our own peril and the human beings whom we reach. 

You can read the full editorial by @badastronomy HERE. He also published a brilliant piece called ‘Answers for Creationists’ simply to use a platform for science education and critical thinking. 

I’ve said this before, but it bears repeating: I think that people have the right to believe what they want. But when that belief clearly contradicts what we know to be true due to our observations of the Universe, and someone is vocal about it, well, we’re going to have a problem.
Phil Plait


In regards to your question about why we can’t see the shape of the Milky Way and why our details are so fuzzy on this seemingly simple question (considering the Milky Way is “our” home), reference the below multiwavelength image from NASA GSFC

We view the Milky Way essentially edge-on from our perspective near the plane of the disk and 28,000 light years from the Galactic center. (x

Each picture is a panoramic photo—if you want an idea of what we really see, imagine taking each picture and wrapping it in a big circle around you. The photographer has simply chosen to “cut” and “unfold” this circle such that the Galactic Center (the brightest part of the Milky Way) is in the picture’s center. This might give the illusion that we are looking at an edge-on picture of the Milky Way from the outside, but in reality we are not—the left and right edges of this picture simply represent material in the Milky Way that is located in the opposite direction of the Galactic Center from our point of view, and since we ourselves are pretty close to the edge of the Milky Way, there isn’t much to see in this direction.

You can also see from these pictures how much “stuff” there is in the Milky Way which prevents us from seeing through to the opposite side. For example, the optical picture has a bunch of dark dust clouds that almost completely block our view of anything within the galaxy. Luckily, these dust clouds are much more transparent to other types of light (for example, infrared and radio) so we can use these wavelengths to look at objects on the other side of the galaxy from us. (x)

Coconut Science Lab shared a brief animation regarding the data-backed hypothesis that the Milky Way is actually a Barred Spiral Galaxy:

Credit: ESO, NASA JPL Caltech, M. Kornmesser, R. Hurt, University of Central Lancashire, V. Debattista (simulation), L. Noel (animation).

Though we tend to think of the Milky Way as a pure spiral galaxy, new research indicates it is actually a barred-spiral, with a peanut-like, or x-shaped, central core. This inner region of our galaxy has the shape of a peanut in its shell when seen from the side, and of a highly elongated bar shape when seen from above.

Barred spirals are quire common in the Universe, though this is the first time that this shape has been clearly seen in our own Milky Way. Simulations have shown that this shape is characteristic of a barred galaxy that started out as a pure disc of stars.

Learn more HERE via NASA/Hubble Space Telescope.

Astronomers now think that the Milky Way started out as a pure disc of stars which formed a flat bar billions of years ago. The inner part of the bar then buckled to form the three-dimensional peanut-shape seen in the new observations. 

The results are based on data from two groups of astronomers, who used ESO telescopes to make a three-dimensional map of the central region of the Milky Way. The peanut-shape was mapped using public data from ESO’s VISTA survey telescope, along with measurements of the motions of hundreds of stars in the galactic central bulge. (x)

Also read ‘SO, WHY IS THE MILKY WAY A BARRED SPIRAL?’ via Robert Massey @caltech

Related: ‘Carl Sagan visits his childhood classroom, and discusses images returned from the Voyager spacecraft, answers questions, and communicates our place in space’ from Cosmos: A Personal Voyage