*** The Official Astronomy & Universe Thread ***

Cosimo said:
Seventy days worth of solar system observations from NASA's Kepler spacecraft show the planet Neptune appearing on day 15, followed by its moon Triton. Neptune's tiny moon Nereid can be seen at day 24.
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Hehe with the pixel resolution, they're using drizzle (actually developed for the hubble) and lots of PSF deconvolution..

Drizzle is where you use lots of little shifts between each image so that when you align the stars, the pixel 'grid' moves across the field of view. When you add the images together, you do so on a grid of 10x the resolution, the result is that you get back details you can't see in a single image.
 
Had the pleasure of listneing to a quick lecture by Prof. Brian Cox a few weeks ago. He made a visit to my place of work, such a nice bloke! His views on future space travel and discoveries were mind-boggling!
 
The binary asteroid Didymos has been chosen as the target for a proposed mission to learn more about near earth asteroids and test deflection and planet defence strategies. ESA’s Asteroid Impact Mission (AIM) is part of the proposal with a planned arrival at the asteroid in 2022:

 
Some lunchtime reading to share.

66 million years ago the dinosaurs were wiped off the planet by an extinction level event. The 100 mile wide crater was found and it's widely accepted this collision was the cause based on the historic records in the layers.

Reading this puts some insight into what is seen as regular extinction events on our planet based on how our solar system orbits the galactic plane as it's not a flat orbit, but a wavy one and because of that, every 30 odd million years we float through heavy areas of space where they now theorise is filled with pockets of dark matter that force asteroids and comets off balance and some of those end up hitting Earth.

So, an event that happens twice every 63 million years or so. Sounds like we are due one any time now then? :p

With that in mind then, does this ultimately mean that future humans finding home elsewhere in the neighbouring galaxy is futile? Let alone Mars or one of the other bodies in our own solar system?
 

This time-lapse movie of an extragalactic jet was assembled from 20 years of Hubble Space Telescope observations of the core of the elliptical galaxy NGC 3862. The blowtorch of ejected plasma is powered by energy from a supermassive black hole at the center of the galaxy. Once the movie was made, astronomers could easily follow the motion of a string of knots moving along the jet. They were surprised to see that one of the knots caught up with and "rear-ended" the knot in front of it, causing it to brighten. The new analysis suggests that shocks produced by collisions within the jet further accelerate particles that are confined to a narrowly focused beam of radiation. The jet is blasting across space at nearly the speed of light.
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mrk said:
Some lunchtime reading to share.

66 million years ago the dinosaurs were wiped off the planet by an extinction level event. The 100 mile wide crater was found and it's widely accepted this collision was the cause based on the historic records in the layers.

Reading this puts some insight into what is seen as regular extinction events on our planet based on how our solar system orbits the galactic plane as it's not a flat orbit, but a wavy one and because of that, every 30 odd million years we float through heavy areas of space where they now theorise is filled with pockets of dark matter that force asteroids and comets off balance and some of those end up hitting Earth.

So, an event that happens twice every 63 million years or so. Sounds like we are due one any time now then? :p

With that in mind then, does this ultimately mean that future humans finding home elsewhere in the neighbouring galaxy is futile? Let alone Mars or one of the other bodies in our own solar system?
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I found this quite interesting even though it's based on the premise of a completely unproven theory (dark matter), so speculative at best.

I'd be interested to see if this 30 million year cycle is documented and being studying elsewhere however. My own personal speculation as to what could cause these disruptive cycles whilst travelling around the galactic plane:

Some kind of increased energy input from the changing environment of the intergalactic magnetic / electric field. This could have a number of effects, including some unknown electrokinetic forces acting on otherwise stable oort objects unprotected by the heliosphere. The sun's energy output could spike or wane, causing activity like solar flares or long term global cooling. Increased energy transfer to the earth via. weak neutrino output from the sun could manifest as increased geological activity as the earth captures this excess energy in it's core and converts it into new mass.

Question is, which part of the galactic oscillation is the most dangerous? can we correlate any of this to the Milankovitch cycles, or is it unpredictable and chaotic behaviour that we have little hope of understanding...
 
mrk said:
Some lunchtime reading to share.

66 million years ago the dinosaurs were wiped off the planet by an extinction level event. The 100 mile wide crater was found and it's widely accepted this collision was the cause based on the historic records in the layers.

Reading this puts some insight into what is seen as regular extinction events on our planet based on how our solar system orbits the galactic plane as it's not a flat orbit, but a wavy one and because of that, every 30 odd million years we float through heavy areas of space where they now theorise is filled with pockets of dark matter that force asteroids and comets off balance and some of those end up hitting Earth.

So, an event that happens twice every 63 million years or so. Sounds like we are due one any time now then? :p

With that in mind then, does this ultimately mean that future humans finding home elsewhere in the neighbouring galaxy is futile? Let alone Mars or one of the other bodies in our own solar system?
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Interesting article, however a fair amount of it is mostly hypothetical and not yet mainstream Physics as far as I am aware. For example, the following claim:

Physicists have argued that the dark matter particles can be captured by the Earth, and will build up in the Earth’s core. If the dark matter density is great enough, the dark matter particles eventually annihilate one another, adding a large amount of internal heat to the Earth that can drive global pulses of geologic activity.
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I don't think I've seen this claim before and I am pretty sure there is no consensus on the hypothesis as yet, however it is an interesting idea and I'm sure the many dark matter based experiments that are ongoing will shine some light on such theories in the next few years.
 
This isn't completely belonging here :p but was just wondering. Do any of you ever listen to Star Talk Radio? It's a podcast radio show hosted by Neil deGrasse Tyson.

I've not been listening to this long but it's really interesting and the shows are pretty funny.
 
colzboppo said:
I found this quite interesting even though it's based on the premise of a completely unproven theory (dark matter), so speculative at best.

I'd be interested to see if this 30 million year cycle is documented and being studying elsewhere however. My own personal speculation as to what could cause these disruptive cycles whilst travelling around the galactic plane:

Some kind of increased energy input from the changing environment of the intergalactic magnetic / electric field. This could have a number of effects, including some unknown electrokinetic forces acting on otherwise stable oort objects unprotected by the heliosphere. The sun's energy output could spike or wane, causing activity like solar flares or long term global cooling. Increased energy transfer to the earth via. weak neutrino output from the sun could manifest as increased geological activity as the earth captures this excess energy in it's core and converts it into new mass.

Question is, which part of the galactic oscillation is the most dangerous? can we correlate any of this to the Milankovitch cycles, or is it unpredictable and chaotic behaviour that we have little hope of understanding...
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PhysicsMan94 said:
Interesting article, however a fair amount of it is mostly hypothetical and not yet mainstream Physics as far as I am aware. For example, the following claim:



I don't think I've seen this claim before and I am pretty sure there is no consensus on the hypothesis as yet, however it is an interesting idea and I'm sure the many dark matter based experiments that are ongoing will shine some light on such theories in the next few years.
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Certainly food for thought, and worth keeping in mind that some things we know to be true today were also hypothetical in the past until they could be tested and quantified so who knows, in years to come, when we have the technology to do just that, people will look back the same way regarding dark matter... perhaps :p

Personally I think it makes some sense, a constant cycle of some 30 million years though whether dark matter had a major play in it or not remains to be seen, could it happen without it though? Our wavy route through the galactic disc could happen regardless no?
 

This artist’s impression illustrates how high-speed jets from supermassive black holes would look. These outflows of plasma are the result of the extraction of energy from a supermassive black hole’s rotation as it consumes the disc of swirling material that surrounds it. These jets have very strong emissions at radio wavelengths.
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Not often we get to hear about Pluto’s moon Nix:



This animation illustrates how Pluto’s moon Nix changes its spin unpredictably as it orbits the Pluto-Charon system. The view is from the centre of the system as the moon circles around it. The time-lapse animation is based on a computer simulation which calculated the chaotic movement of the four smaller moons in the Pluto-Charon system. Astronomers used this simulation to try and understand the unpredictable changes in reflected light from Nix as it orbits Pluto-Charon. They also found that Pluto’s moon Hydra undergoes a chaotic spin as well. The football-shape of both moons contributes to their wild motion.
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