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ajpoolshark

General Astronomy/Cosmology Thread

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A warm welcome to the new NetWeather Astronomy & Cosmology thread. This thread has been designed to encompass all aspects of astronomy for all levels of expertise, from a casual interest to the 'would-be Stephen Hawkins'!

 

So please feel free to browse and ask any questions you might have, and I'm sure there will be plenty of members ready to discuss the answers.

 

There are a whole raft of resources available on the internet so I'll post a few links below, and feel free to add your own links in what is a diverse and fascinating field of study.

 

http://www.eso.org/public/

http://www.nasa.gov/

http://www.space.com/

http://www.sciencedaily.com/news/space_time/

http://en.wikipedia.org/wiki/Astronomy

 

I'll kick off the discussion with a question that was posed by Snowlady36

 

'How fast is the universe currently expanding?'

 

An interesting question!. The best I can come up with is from well known TV astronomer Phil Plait, host of Discovery Channel's 'Bad Astronomy'.....According to his interpretation, the universe expands at a rate of 74 Kilometers per second per every 3 million light years of distance.....here's the link

 

http://blogs.discovermagazine.com/badastronomy/2009/05/07/the-universe-is-expanding-at-742-kmsecmpc/#.U06z71e59tA

 

 

Can anyone else come up with a different answer?

Edited by ajpoolshark
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The Spitzer telescope has now measured the expansion rate (i.e. the Hubble constant) to an accuracy of 3%. This can be combined under certain assumptions with other results (e.g. WMAP) to get an accuracy of 1% and a value of 69.3 km/sec/Mpc. Dark energy is causing the expansion rate to increase over time, so the universe is flying apart at an ever increasing rate. The best candidate for dark energy is the energy associated with empty space, due to virtual particles.

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Just so ye guys know, Dr Chris Adami is doing an AMA (questions and answers) on /r/science on reddit, here http://www.reddit.com/r/science/comments/236ap1/science_ama_series_im_chris_adami_the_guy_that/

I am a theoretical physicist and computational biologist working at Michigan State University. I'm perhaps best known for the Avida digital life platform, and figuring out that entropy can be negative in quantum physics.I use the concept of information to understand physical and biological systems. My lab focuses mostly on understanding the evolution of complex systems. I recently proposed a solution to the so-called "black hole information paradox" that only uses known physics, and that completes the framework to describe black holes proposed by Stephen Hawking. You can ask me about black holes, information, evolution, whatever. I have a blog called "Spherical Harmonics" that covers topics closely aligned with my research. I used to be a rocket scientist (winning the NASA Exceptional Achievement Medal while working at the Jet Propulsion Laboratory). I am now planning a new institute to use evolution to create artificial intelligence.Here's proof that it's me: http://i.imgur.com/Nzif75W.jpg]

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Mars has brightened impressively over the past couple of months and reached opposition on 8th April, when it was about 57.4 million miles away from Earth. It must be brighter than Sirius now.

 

I remember the really close opposition in August 2003 (34.6 million miles away) when Mars outshone Jupiter. We'll get nearly as close again in July 2018:

 

http://cseligman.com/text/planets/marsoppositions.htm

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Probably going to sound daft but u know the saying to infinity and beyond ... What is beyond ? Is there any such thing as infinity if so how do we know ?

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snowlady36, on 18 Apr 2014 - 00:09, said:

Probably going to sound daft but u know the saying to infinity and beyond ... What is beyond ? Is there any such thing as infinity if so how do we know ?

In short, infinity just means going on for ever, without end. You can never reach infinity and therefore you can't get beyond it. There is no actual number that represents infinity as it's an abstract concept.

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Sen—Last week, the fascinating news was announced that an Earth-sized planet, which is probably rocky, had been found in the habitable zone of a red dwarf star.

Though that tells astronomers water could exist as a liquid on the surface, it is quite another matter to discover whether the planet, labelled Kepler-186f, does in fact play host to life.

With the prospect of future telescopes on the ground and in space becoming ever more powerful, some scientists are already turning their attention to ways they might look for signs of life on nearby exoplanets.

One expert in the field is Dr Lee Grenfell, of the Institute of Planetary Research in Berlin, part of the German Aerospace Centre (DLR). He is testing techniques to detect evidence of alien life from the atmospheres of exoplanets.

Such biosignatures might include particularly high levels of gases such as methane and nitrous oxide which are given off by microbes and so could indicate the presence on the planet of lifeforms.

Grenfell told Sen: “We think it will be possible with next-generation telescopes to detect such signals from close-by terrestrial planets, providing conditions are right. One of the challenges right now is to draw up a long enough list of planetary targets to examine.

“Then we will have to be able to measure such signals. They will be very weak and so technically to have the ability to measure them, we need very powerful telescopes.â€

 

http://www.sen.com/news/astronomers-prepare-to-look-for-life-on-alien-worlds

 

 

Edited by Polar Maritime

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Previous simulations of the growth of cosmic structures have broadly reproduced the ‘cosmic web’ of galaxies that we see in the Universe, but failed to create a mixed population of elliptical and spiral galaxies, because of numerical inaccuracies and incomplete physical models. Moreover, they were unable to track the small-scale evolution of gas and stars to the present epoch within a representative portion of the Universe. Here we report a simulation that starts 12 million years after the Big Bang, and traces 13 billion years of cosmic evolution with 12 billion resolution elements in a cube of 106.5 megaparsecs a side. It yields a reasonable population of ellipticals and spirals, reproduces the observed distribution of galaxies in clusters and characteristics of hydrogen on large scales, and at the same time matches the ‘metal’ and hydrogen content of galaxies on small scales.

http://www.nature.com/nature/journal/v509/n7499/full/nature13316.html

 

http://www.bbc.co.uk/news/science-environment-27299017

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First clear evening in about 3 weeks tonight. Saturn, which I've been waiting to get a look at with the binoculars, has now gone through opposition (last time I saw it it was due south about 2am) and we finally get a clear night when the moon is right by it. So thats that one ruined.

Jupiter is now getting low, though still prominent and showing its Galilean moons in the bins. Orion has gone; it was still fully visible last time it was clear.

But Saturn being a non starter was made up for by seeing Mercury for the first time in over 2 years. Its quite easy with a clear horizon to the NW about an hour after sunset. Best chance this year for the next 2 weeks, Not much to look at in binoculars, but always feels good to.spot it

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NEW METEOR SHOWER ON EARTH AND THE MOON: Anticipation is building as Earth approaches a cloud of debris from Comet 209P/LINEAR. This weekend, meteoroids hitting Earth's atmosphere could produce a never-before-seen shower called the "May Camelopardalids" peaking with as many as 200 meteors per hour. The best time to look is on Saturday, May 24th. http://www.spaceweather.com/

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Rare cosmic blast sends astronomers racing to telescopes.

NASA’s Swift satellite has detected a burst of high-energy gamma rays coming from the Andromeda galaxy, the closest large galaxy to the Milky Way. The rare cosmic explosion is likely to deliver a flood of data to astronomers, who are swiveling their telescopes to capture its aftermath.

Posted Image

The Andromeda galaxy. Credit Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF.

Swift watches for gamma-ray bursts and, if it detects one, the satellite automatically redirects to try to capture the source. The trigger went off at 9:21 pm Universal time on 27 May; three minutes later, the X-ray telescope aboard Swift was already observing a bright X-ray glow where none had existed before.

News of the event rippled across the astronomical community. Within minutes the Swift data servers had crashed, leaving the official news mirrored in unofficial locations.

Edited by Polar Maritime
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Another reddit AMA you folks might find interesting http://www.reddit.com/r/science/comments/26otuz/science_ama_series_i_am_shaun_hotchkiss_a/

 

He'll be answering questions from 6pm onward. Here's his bio,

 

Science AMA Series: I am Shaun Hotchkiss, a theoretical cosmologist studying inflation and the large scale structure of the universe, AMA.

Hello /r/science , I'm Shaun Hotchkiss. I research cosmology. I'm a post-doctoral researcher based at The University of Sussex, in England. You can find my research website here.

The things I've done active research on are: building and testing models of cosmological inflation, using the masses of the biggest galaxy clusters to probe the initial conditions of the observable universe, predicting the gravitational effects that cosmological structures have on light as it passes through them and finding and cataloguing cosmological "superstructures" (really big regions of the universe that are much more or much less dense than average).
I will be around from 6pm BST, 7pm CEST, 1pm EDT, 10am PDT, etc. I might have made a mistake in the timezones. To be safe, I live in the UK and will be online from 6pm our time.
I'm happy to answer any cosmology/science based questions. I'm also a kiwi, who has spent more than seven years living in Europe, including three in Finland, so feel free to ask about the life of a scientist and what it's like. I also think more scientists should enter politics, feel free to ask me about that. Basically, AMA (well, anything that /r/science will let you get away with!).

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Rare cosmic blast sends astronomers racing to telescopes.

NASA’s Swift satellite has detected a burst of high-energy gamma rays coming from the Andromeda galaxy, the closest large galaxy to the Milky Way. The rare cosmic explosion is likely to deliver a flood of data to astronomers, who are swiveling their telescopes to capture its aftermath.

Posted Image

The Andromeda galaxy. Credit Bill Schoening, Vanessa Harvey/REU program/NOAO/AURA/NSF.

Swift watches for gamma-ray bursts and, if it detects one, the satellite automatically redirects to try to capture the source. The trigger went off at 9:21 pm Universal time on 27 May; three minutes later, the X-ray telescope aboard Swift was already observing a bright X-ray glow where none had existed before.

News of the event rippled across the astronomical community. Within minutes the Swift data servers had crashed, leaving the official news mirrored in unofficial locations.

That now links to a story entitled "False alarm of cosmic blast sends astronomers racing to telescopes". Someone seems to have mistaken something already there for something new.

Edited by Crepuscular Ray
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Yes seems that way CR, Never noticed the update this morning  :oops:

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Astronomers Find a New Type of Exoplanet: “Mega Earthâ€

 

Oh, that tricksy nature. Just when we think we won’t be surprised by what we find, we find, well, a surprise. In this case, astronomers have discovered that a nearby star has a kind of planet never before seen: a “mega Earth,†a rocky planet far larger and more massive than our own.

Posted Image

 

 

 

http://www.slate.com/blogs/bad_astronomy/2014/06/03/mega_earth_the_large_rocky_planet_kepler_10c.html

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Universe's Expansion Measured With Unprecedented Precision.

 

Scientists studying more than 140,000 extremely bright galaxies have calculated the expansion of the universe with unprecedented accuracy. http://www.space.com/26279-universe-expansion-measurement-quasars-boss.html?utm_content=buffer26090&utm_medium=social&utm_source=twitter.com&utm_campaign=buffer

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