Exeter's space thread!

Just a couple interesting images for your day!


This is called an analemma, and it reflects the sun's apparent position in the sky over the course of a year. It comes from the motion of the Earth around the sun, combined with our axial tilt and how it changes over the year. In winter, the sun ia at the lowest point, in summer, it's at the highest.


Here you have Planetary Nebula Shapley 1, a result of a star ejecting its outer layers as it reaches the later stages of its life.


And here you have galaxy ESO 510-13, which is warped for some mysterious reason, possibly an encounter or even a collision with another galaxy sometime in the ancient past.

 

Some info about NASA

 

Any two planets have an orbital resonance that describes the relationship between their two orbits. For Earth and its smaller sister Venus, that's 8 Earth orbits for every 13 Venus orbits, approximately. Remember Keplar's third law of planetary motion, the closer you are to the sun, the faster you orbit around it. Here's an illustration of what this symmetry looks like, without all the messy details that actually make this picture technically inaccurate.

 

Hehe... Anal....

I'm so mature

 

For anyone interested in where we may settle outside of earth, here is the Wikipedia article on SPACE COLONIZATION

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

 

Anal comes from anus which has a latin root in the word for a ring, analemma comes from a greek root for the pedestal of a sundial.

ETYMOLOGY STRIKES BACK!

I actually just wanted to know if they shared a common root

 

Astronomers using Hubble discovered a Supernova taking place in an extremely distant galaxy, embedded in a dense cluster of galaxies.

Because of the effects of gravity, the light from the supernova was bent around a galaxy in four different directions. Not only that, but the astronomers suspect the supernova's light already took a different route through the gravitational maze and was probably visible 20 years ago. AND it will probably be visible again in about 5 years as the light takes yet another path.

 

I'm loving this thread <3

 

Contribute!

 

Thought I'd share some lovely gifs of space stuff that always pop up on my tumblr!

 

I was just outside and I saw for the first time the Big Dipper on the night sky. Or Plough as it's called in the UK. I had to look up the names, here in Sweden it's called Karlavagnen. Anyway I can honestly say I was starstruck (pun intended) and I was once again in awe over how beautiful the sky is at night.

 

In honour of your sighting, here are some lovely images to celebrate Ursa Major ^^

Vincent van Gogh's Starry Night over The Rhone


It features on the Coat of arms of Sweden as a crest for the royal family of Bernadotte

Just a typical view of the asterism (A constellation is a defined area of sky. An astronomer may say an object is in the constellation of such-and-such, meaning that the object is within the defined region, not specifically between the apparent positions of the stars of the asterism.)


A card from the set of constellation cards published in 1825, Urania's Mirror. Note that the bear has a tail! There are all kinds of silly antiquated reasons for this. Jewish astronomers consider the three stars of the tail or handle of the plow to be cubs following the mother. Native Americans saw them as hunters.


Arabic astronomers named most of the stars you'll ever see with a naked eye. The stars that make up the asterism of the "dipper" are called, Dubhe, Merak, Phecda, Megrez, Alioth, Mizar (Actually a binary star with a companion called Alcor, and Alkaid (or Benetnash). Of course they have more astronomical names too but they're less interesting!

 

The Cassini spacecraft, which is orbiting Saturn (launched in 1997 and arrived around 2004) just reported some interesting finds.

Scroll past the photos for the story!



You can actually see that the E-ring around Saturn is being actively contributed to by the water coming out of Enceladus.


The moon Enceladus is covered in a thick ice sheet. However, geysers of water have been spotted shooting plumes from small cracks in Enceladus's surface. These have been known about for quite some time and are indicators of some the interesting features of this tiny world.



Scientists have found microscopic rock grains near Enceladus, which indicate hydrothermal activity is taking place within. There are a number of ways of heating an icy little world, radioactive materials in the core can keep it warm, the effects of gravity can produce heat from orbit, as the small world is tugged, stretched, and squashed as it zips around Saturn. There's even some math suggesting that Enceladus was more massive in the past, but has lost about 30% of its mass over its lifetime, changing the conditions that were present when it first formed and became stable, and this could lead to degrees of tectonic activity as the now lighter moon behaves differently.

The rock grains are the first proof of hydrothermal activity on an icy moon, telling us that water from the ice interacts with the crust of the moon and comes out of those geysers bearing minerals.

This is significant because if there's water and some heat and a rich chemical composition available, we might just discover life hiding out under the ice!

 

Well, page 3 of this thread crashes my iPad at about the NASA infographic for some reason, but been enjoying what I've read so far! Glad I came back to find this thread.

Definitely hadn't known about the lensing of light with regards to duplicate images of galaxies... makes me wonder how many galaxies/clusters Hubble has seen that are actually just duplicates! Always kinda awesome and unsettling (in a good way) realizing not everything you see is as it seems. Not to mention how you're never seeing one continuous, contemporaneous snapshot of time when you look up there in any given direction. Damn, space, you freaky!!

 

I've posted a lot of gifs and images here, I really recommend a PC and apologize for the heavy content, I'm glad you've been enjoying it though!

The big question in cosmology for the longest time was "What is the shape of the universe?" We had to do a lot to figure it out, primarily it involves weighing the universe and figuring out if there's enough stuff in the universe to make it geometrically closed, flat, or open. In a closed universe, you could look out in any direction and eventually see the back of your own head. We don't live in that universe though, ours is geometrically flat, not that it means much to us here at this scale, but it has something to do with the way we think about space.

Light is how we map the geometry of space. Light moves in straight lines and the global geometry of the universe determines what happens to those straight lines in the long run. In the short run, massive objects warp space because of general relativity, making those straight lines curve. In a closed universe, parallel lines (paths light can travel in) converge, and you get that when you have too much stuff in your universe. In a flat universe, they stay equidistant over time, and a universe like that has zero total energy, that is to say the mass of all the stuff is counteracted by the negative pressure of empty space, or what we call Dark Energy. In an open universe, they diverge and never again meet. The only thing that screws that up is gravity. There's a lot of dark matter out there, and whatever it is, it's what makes light in those images do weird things. There's nowhere near enough baryonic matter in those galaxies, even in those whole clusters to do that. Only the mysterious stuff that makes up 30% of the universe's energy density can do that. Whatever Dark Matter is, it's making space lumpy and chunky and bending straight lines into all kinds of weird shapes.

 

No worries on the amount of content! More, more!

My friend and I were discussing just a few months ago whether dark matter is a three-dimensional representation of a fourth-dimensional object. I love just pondering the possibilities of what it might really be, and knowing there's such a great amount of stuff out there that we can't even describe or categorize completely.

This conversation came upon reading some material about black holes potentially being our third-dimensional view of a fourth-dimensional hole, and how such a hole would operate. And the theory that our entire universe is inside a black hole--which makes an eerie kind of sense, considering the Big Bang requires (among other things) the assumption of a singularity of incredible mass at its beginning--something which is apparently otherwise difficult to shoehorn into our other understandings of physics. I love this theory, and it's what made me suddenly not so terrified of black holes, if indeed we were born from one (i.e. not so bad being inside one in that case; just maybe not trying to make the transition across that boundary). The one thing that saddens me about it: if true, we (theoretically) can never see what's outside our universe (or even attempt to reach the limits of it), or see what other universes might exist inside other black holes.

Then again, it's that catch-22 of wanting to know everything, but loving having things to ponder endlessly--with at least the potential we could one day understand everything, mind you (even if that day never comes due to the ultimate constraints of time). This thread does make me wish, again, that I'd sprung for the Astronomy degree after all (was really more my first choice) instead of just the generalized Earth and Ocean Science degree... or that I'd more thoroughly considered the application of earth sciences to other planets (Astrogeology and, hopefully one day, Astrobiology anyone??). Don't get me wrong, I love Earth, and we do still have things to discover. But on-Earth, near-Earth and, to a degree, near-space physics is just more predictable and better understood. The vastness and nigh-incomprehensible forces and realities at work in deep space are so very alluring by comparison--and can sometimes lead to newer understanding of how even everyday, Earth-centric physics actually works.

 

Dark Matter could be a whole lot of things, but the first mistake we make is assuming it's any kind of matter at all. Dark Gravity is really a better name for it, because all we see are its effects, and that's not enough at this point to lead us anywhere else. There are all kinds of ideas out there, gravity shadows from other universes, weakly interacting particles with high mass, completely unknown features of string theory, but ultimately, all we know is that there's a lot of gravity out there in apparently empty space, for reasons unknown. Of course, if we should ever come up with a working quantum theory of gravity, we'll have gravitons to think about, and then we'll have to explain where they're coming from in regions where dark matter appears. I suspect that telling the story of Dark Matter will tell us the missing part of the story about gravity.

Another feature of warped space inside a black hole is that when you look back out, the entire future of the universe is falling in towards you, and you can see it all unfold quite rapidly. If our universe is indeed inside a black hole, maybe there's really nothing to see beyond the event horizon, or maybe space is just expanding so fast that the light from beyond is invisible now, stretched on the fabric of space into wavelengths wider than we can detect. Either way, we can't see back very far because of the Cosmic Microwave Background Radiation, so if there was a feature outside our universe to look at from the inside, it's obscured today by opaque radiation from the distant past.

Stephen Hawking recently made an announcement that he didn't think event horizons exist. One problem they create is that of firewalls, intensely radiant barriers created around the "Event horizon" where hawking radiation breaks multiple (impossible) simultaneous entanglements and releases a vast amount of energy, violates Einstein's ideas about black holes. Without event horizons, the information (quantum states, energy) that go into a black hole would eventually be able to escape as radiation. The event horizon is thus replaced by a region marked by violent radiation and utter chaos. Still the scariest imaginable place to be, but at least your quantum information might escape some day!

Hey, life is long and you can always expand your knowledge. Planetary Science is still a rich field with many discoveries waiting to be made. Ocean sciences will be essential for exploring Europa and Enceladus, AND Titan has hydrocarbon seas waiting to be studied. Geology is essential for studying the rocky bodies of the solar system, and while a lot of geological processes don't really occur in the vacuum and low-gravity environments out there, there's still an enormous amount to learn about our local planets, let alone the hundreds we've discovered around other stars here in our galactic neighbourhood. The new worlds waiting to be explored will be explored by scientists across a spectrum of fields.

 

@othersounds Just thought of some other neat facts about the Big Dipper!

The stars are not really very close together, though some of them are, and they likely formed around the same time. Their actual relative distances from Earth are as follows.



The stars in the sky wheel around and appear in different directions at the same hour in different seasons. The Big Dipper is Circumpolar and always visible above the horizon for those in the northern hemisphere. Here's where it can be found at midnight across the year.



As all stars are in motion, the apparent position of the stars in the asterism will change over time and has changed since our ancestors first looked up and wondered what it was.

 

I'll try and get some Eclipse photos on Friday! Hope there's a clear sky but it's not looking hopeful.

 

That's really neat! It doesn't surprise me but it's still something I never really thought of. Also the Dipper of 100,000 years ago looks a bit like a spear. That's kinda cool.