milky way and andromeda collision

we all live on a pale blue dot we call earth, which orbits around the sun, along with many other planets, rocks, and dust, to form our solar system. the sun, along with about 400 billion other stars, make up our the milky way galaxy. the milky way galaxy is one of the biggest galaxies inside our gravitationally bound local group of galaxies. there are roughly 45 observed galaxies in our local group. the milky way and the andromeda galaxy (M31 - shown below) are the largest galaxies in our group, while the others are all tiny little asymmetrical things like the clouds of magellan (small and large), the draco dwarf galaxy, the carina dwarf spheroidal galaxy, et cetera, and my new personal favorite: dwingeloo 1 (i just think the name is awesome)!



the milky way and andromeda galaxies dominate our local group. they dance around each other, spinning in circles around their shared gravitational center, while all the small galaxies cluster around the two big ones. slowly, the two massive spiral galaxies will shrink the distance between them, spiraling closer and closer, until they eventually become one galaxy. i say they are moving slowly because it will take them another 4 billion years or so to fully merge, but andromeda approaches the milky way at 300,000 km per hour!!!

our visual intuition of what a galaxy merger looks like is generally not what really happens. you see no massive fireworks that you might assume would occur when those billions of stars smash into each other. the thing is... stars nearly *never* come into violent contact! the distance between individual stars is so huge, that even though both andromeda and the milky way have hundreds of billions of stars each, it will be very unlikely that any two will get close enough to feel each others heat! just think that our sun's nearest stellar neighbor, alpha centauri, is 4 light years away! it takes *light* 4 years to travel to the closest star to our sun. thats *very* far away! even inside of densely packed globular clusters, star dont collide.

so if nothing explodes when galaxies collide, what do mergers look like? here are some examples of simulations that show the eventual merging of andromeda and the milky way. the merger will take place in about 4 billion years, so nothing to fear... don't worry! in fact, if humans were still around as that time approached, it would be fantastic because you could see the andromeda galaxy shining in the sky! you can see it now with the naked eye as a tiny little smudge... if you know where youre looking on a very clear night.

here's a quick video showing how the two massive galaxies will come together. the first time they go near each other, they pass thru each other like ghosts (no fireworks). gravitational forces dominate the interaction, drastically warping each galaxy.



this excerpt from a full program shows the collision in a bit more detail. the video clip describes the sloan digital sky survey during the first 4 minutes (this is where the galaxy zoo gets its millions of galaxies), and then shows visualizations of the milky way - andromeda collision starting around minute 4. they also show what the night sky might look like from earth's surface when the warped milky way disk and the beaming bright andromeda spiral dominate the view!



here's a scientific simulation produced by the N-Body Shop at the university of washington. props to them for displaying their very cool, physically motivated simulations on youtube for all to enjoy! this video shows how the milky way galaxy may have formed, with many small objects coming together under gravity's influence to form one galaxy.

watching comet siding spring approach mars

i work with a very interesting doer-of-all-astronomy-tech-things steve lee (of "Steve and the Stars" fame).  over the last couple nights, as comet siding spring has rushed towards mars at 56 km/s, steve has been taking images using two of his own telescopes that live near siding spring observatory in new south wales, australia.

the distant astronomical objects i study in the universe do not really change or move noticeably in the time that i've been studying them (or even over a human lifetime).  so i find it very exciting to be able to watch a comet zoom across a field of view over the period of 24 hours!

here are two images of comet siding spring, mars, and milky way dust taken 24 hours apart using the same setup (90mm refractor + Canon 6D, 7x1min exposures summed), but cropped slightly differently. you can clearly see the motions of both the comet and mars again the background stars and dust contours of the milky way galaxy.

Comet Siding Spring, Mars, and Milky Way dust taken 18 Oct 2014 by Steve Lee

Comet Siding Spring, Mars, and Milky Way dust taken 19 Oct 2014 by Steve Lee 

now for a different comparison - here is an image of the same region of sky, but captured through a different telescope setup and exposure detail (31cm f/5 Newtonian + Canon 6D,  single 2 minute exposure).

Comet Siding Spring, Mars, and Milky Way dust taken 19 Oct 2014 by Steve Lee

cool stuff.

view from the disk

a few days ago, the astronomy picture of the day featured an image taken by photographer, Larry Landolfi, near the mcdonald observatory in west texas. i've never seen the milky way look this crisp with my eyes with the foreground so illuminated... he uses a neat "composite" trick where he takes several images and puts them on top of each other to get a really neat effect. he has some other amazing photographs that you should really check out!


last month i introduced the following picture of our milky way and described some of the features of our flat galaxy. this might be a confusing image of what our galaxy looks likes, but remember that we're inside the big disk looking out thru it.


now, imagine if we could jump in a space craft and fly away from our galaxy, but still sit in line with the disk. we take our trusty hubble space telescope (of course!) and fly 50 million light years away... then turn around to take an image of the milky way.... our view might look like this picture of the "edge on" galaxy, NGC 4013... you can still see the star light shining around the central line of dark dust clouds that block some of the light produced by the stars.


if we fly even farther away, in order to get the whole of the galaxy in the view of our telescope, we might see something like the "needle galaxy" (NGC 4565) that even shows a concentration of bright light at the very center. its difficult to tell exactly what the very center of our galaxy looks like since we're sitting inside it (did you ever see that movie inner space?). maybe the needle galaxy has a lot of stars at its center, or lacks the dust there that would block the starlight from escaping, or maybe there's a massive black hole in the center energizing the surrounding gas to the point of glowing!


now we're out in space and we decide to sit back and look around. we spot this crazy disk galaxy... we call it the pizza dough galaxy, but learn that astronomers on earth all call it ESO 510-G13.


it looks like it could consist of a flat disk of stars and dust like our milky way, but there's a big warp in it. it almost looks like pizza dough as it spins through the air above some brave person's head! thin disks are actually rare and very fragile. a small gravitational bump could cause a disk to distort just like this! they're hard to find in the universe since galaxies are so far away... we're lucky to have such good telescopes to find such cool looking galaxies!

think about what it would look like across our sky if the milky way's disk had a big warp in it like the pizza dough galaxy!

more life in the universe

i believe life... in some form... exists somewhere in the universe other than just on earth. the universe is just too big for us to be the only life!! we developed on one planet, among nine eight planets that orbit around one star in the milky way galaxy which harbors ~400 BILLION other stars. the milky way is only one galaxy among the BILLIONS of galaxies in the universe, each containing BILLIONS of stars. any of those stars could have planets, but planets are really hard to find!

i'm certain life exists *somewhere* in that vast volume of space, but that's exactly the difficulty in finding life.... there are so many galaxies and stars so where do we look? what do we look for? since we live on a planet, we can easily deduce that the best place to look is on other planets! as of today, we've detected 233 planets outside of our solar system and its cool that we finally found an earth-like planet that exists in a region around a star with a temperature to support liquid water!

life on earth has existed for 5 billion years but the universe is about 13.7 billion years old. some life out there could have just began in the last billion years or less, or some planets could have harbored evolving life forms for twice as long as the earliest known life forms believed to be on earth! that raises interesting questions about what life on earth might look like in another 5 billion years (assuming life survives this destructive period in human existence)! consider that only 65 million years ago, dinosaurs dominated earth's surface!

communication with extraterrestrial lifeforms is a whole other issue. our chance of "communicating" with anything out there (in my opinion) will result from another civilization communicating with us. we've been sending off electromagnetic signals for, lets say, 100 years. the earliest signals are now 100 light years away from earth in all directions. within that sphere there are only ~30 stars. the new planet we just found is about 20 light years away... so it has received our earliest transmissions and has had ample time (over 20 years) to send a light signal back our way. We havent received any signals from this or any other planet accoring to the SETI Institute. our (unintentional) early electromagnetic signals have only reached a few dozen stars among the buhzillions that exist in the universe... and thats traveling at the speed of light!

so.... thats why i say our best chance for communication is from another life form having sent out a signal at some point in the past. let's say there's intelligent life on a planet on the other side of the milky way... about 40,000 light years away. if we receive a signal tomorrow from this distant planet, the signal will have been traveling from that planet for 40,000 years! we are ready with our return signal (of course!), which we send out immediately. that planet will start receiving our original signals in 39,900 years and then in 40,000 years, they will receive our response specific to their message. then it will take them 40,000 years to respond to us, etc....

another (more hopeful) option is that they will have detected our presence thru light detection or exploration of our neck arm of the milky way, in space vehicles that travel very very fast!!

my point is not to lose all hope of ever detecting another civilization... on the contrary, i think it is super exciting that we are detecting so many planets so rapidly right now!! my real point is that there *has* to be life out there somewhere is this unfathomably large universe of ours. probability says there should be life considering the volume and the fact that the chemistry that makes life possible on earth is extremely abundant throughout the universe. so let's keep looking and doing our best not to destroy our own successful and immensely special civilization while we are actively searching for those signals!!

halo around the milky way galaxy

all the light in the universe that our eyes can see comes from stars.

but stars are only one constituent of our milky way galaxy, which also has gas and dust and a lot of other stuff that i've described before. we use wavelengths of light that our eyes are not sensitive to (X-rays, infrared, radio, etc...) in order to detect some of this other stuff. 

it's much more challenging to detect stuff in the universe that doesnt produce light that we know how to see.  for instance, dark matter makes up 25% of all the stuff in the universe, but we dont know exactly what it is yet because we dont know how to "see" it (although we can infer its presence in other ways).

all the "normal" stuff in the universe (planets, stars, gas, trees, humans, etc...) is made of what we call baryons, and it only makes up about 4% of all the stuff in the universe.    the problem is that we havent actually found all the baryons that our otherwise very successful theories tell us there should be.  this has been referred to as the "missing baryon problem" and has been studied for a while.

recent results released by NASA using the chandra x-ray telescope suggest that new observations may help solve this mystery, by detecting a hot halo of gas that surrounds our milky way galaxy. 

above is an artist's illustration of the results (since we cant yet fly away to get an outside perspective of our cosmic home, unfortunately).   the blue color shows a very diffuse, and therefore very difficult to detect, cloud of hot gas surrounding our milky way galaxy and our nearest neighboring galaxies, the small and large magellanic clouds.

if all galaxies are embedded in such diffuse clouds, this could account for much of the previously missing baryons.  the results will have to be verified with some other technique before they are completely believable, but this is a nice start!

the emu over parkes

this gorgeous photo was taken by a student who has been working with me in australia for the last several months.  she took some time to travel around the country a bit and captured this wonderful photo at parkes observatory. 

Photo Credit: Gabriela Iacobuta

at the bottom of the photo is the parkes radio dish, glowing slightly during the long exposure.   stretching up into the night sky is the long milky way galaxy.  the dark, cloudy patches of the milky way, the dust blocking the stars shining behind it, are the basis of a very famous australian aboriginal astronomical feature: the emu. 

i didnt see the emu in the milky way when i first arrived here.  maybe that's because i didnt really know what an emu looked like!  they are big huge birds:

Photo Credit: Link

do you see it now?  no?

Photo Credit: Barnaby Norris

hopefully that image helps!

i can usually see the emu now - its head is the dark patch (coalsack nebula) right by the southern cross and then it stretches all the way across the sky!   i think its fascinating that in addition to creating images by connecting the stellar dots across the sky, the aboriginal cultures created stories about the regions of the sky that lack stars.... the dark spots!

The Milky Way Galaxy: A Memoir

Galaxies like me live for hundreds of billions of years, which seems like a long time, but a lot has happened in the mere 13 billion years of my existence so far. My life has been anything but boring.


Galaxy Birth

The memories of my very first years remain fuzzy and diffuse, but I know I came into existence soon after the Big Bang. The first stars that formed in the Universe were BIG! So big that they lived very brief and powerful lives and quickly exploded, causing a series of events that resulted in my formation!

The energy from the explosions of the first stars initiated the gravitational collapse of huge halos of material. I am the result of one of these gravitationally bound systems. When I was born I contained lots of dark matter and gas, which quickly churned into thousands of millions of stars.


Star Formation and Supernovae Explosions

Hydrogen gas was the fuel inside me that I turned into a range of stars, big and small. The stars were either born as twins, gravitationally bound to each other as they slowly moved around my center every 200 million years or so, or they formed their own planets, or both!

I contain about 400 billion stars today and continue to form new stars at a steady rate of a few each year. I probably harbour more planets than stars, but the planets are very hard for me to sense since they are so tiny and do not produce their own light.

A recently discovered supernova in the Pinwheel Galaxy.  Image Credit:  LCOGT

My biggest stars shine very brightly from nuclear fusion in their cores, turning hydrogen into helium and eventually into oxygen and carbon. During my adolescent years of formative star formation, which lasted several billion years, once every hundred years or so one of the most massive stars in my spiral arms would explode as a supernova, sending surrounding gas flying forcefully out in all directions.

When I was young, the gas near the supernova left me for good and was lost in space, because I wasnt yet big enough to gravitationally keep hold of it after the explosion. Eventually I gained enough mass, by collecting more loose gas and forming new stars, that I was able to hold onto almost anything that passed nearby, including other very small galaxies!

My life progressed in much the same way for a few thousand million years, and I grew massive enough that supernova explosions no longer blew away my loose gas.


Supermassive Black Hole

One year I realized something was growing deep inside my core. It felt like indegestion, but it was actually a supermassive black hole! No one seems to know exactly how the supermassive black hole initially formed at my center, but almost every massive galaxy that has been thoroughly examined has been found to bear one as well. Strange, huh?

I first noticed my supermassive black hole because the material near my center was swirling in closer and closer and heating up. During my supermassive black hole's most active phase, the gas in my core reached temperatures of millions of degrees and started emitting X-ray radiation into space.

This active phase only lasted a few million years before the supermassive black hole exhausted nearly all the energy around my core and quietly faded away, to the point where I sometimes forget it's still there.

One species of tiny lifeforms on a planet named Earth, 26,000 light years from my center, calls the region around my supermassive black hole Sagittarius A* (pronounced "Sagittarius A star"). The mass of the black hole at my centre is four million times the mass of that planetary system's sun.


Merging with Neighboring Galaxies

I live in a small neighborhood of galaxies unimaginitely called the Local Group. There are about 50 of us living here, gravitationally bound to each other despite the expanding universe around us. I'm the most massive galaxy in the group, and there is one other big spiral galaxy nearby called Andromeda.

Arp 271 - a hint of what the Milky Way and Andromeda might do one day.

Since my gravity is the strongest in the neighborhood, I recently devoured a few dwarf galaxies living nearby. They remain visible though, as streams of stars orbiting around my central core.

My biggest gravitational attraction is to the Andromeda galaxy, which lives a mere three million light years away. The two of us are slowly spiraling toward each other in a fateful gravitational dance that will guide us to become one massive, egg-shaped galaxy in a few billion years.

The space between our individual stars is so huge that probably no two stars will collide during our eventual merger, but their orbits will change completely and my beautiful spiral arm disk will be destroyed as a result.

Despite losing my shape and gaining so much more mass, I'm looking forward to merging with Andromeda. Its spiral shape will look incredibly beautiful in the sky as we gradually approach each other, and our merger is sure to form a whole new generation of stars.

I've always been referred to as the Milky Way Galaxy by the inhabitants of Earth, but I wonder if I will acquire a new name for the next phase of my life. Something to look forward to!

the milky way project

the fine folks who brought you the galaxy zoo have just revealed another of their endlessly creative and interactive tools: the milky way project!

you can now view our Galaxy in the fantastic colors of infrared light provided by the spitzer space telescope. not only can you enjoy looking at the beautiful features spread throughout our home galaxy, you can help astronomers identify bubbles, knots, stars clusters, supernova remnants, never before-seen distant galaxies and any other strange new objects that look intriguing to your eyes. ultimately, we need to better understand the physics of the mysterious cold, dusty material that emits light at infrared wavelengths and now its possible for you to help!

"The material that we see in this project is dark to the naked eye. By looking in the infrared we pick out material that is not hot but rather cooler, and hence it does not emit visible light, but instead lower-energy infrared wavelengths. However there are still regions of yet colder and denser material that remain dark even to Spitzer's infrared red eye. These infrared dark clouds are stark silhouettes on the brighter, usually green material seen in the images on this site."

see that big dark spot in the middle of the image below? its a "dark nebula" and is possibly a private nursery where new massive stars are forming, hidden by a curtain of cold gas and dust!

here is a quick tutorial demonstrating how easy it is to interact with the images:


The Milky Way Project - Getting Started from The Zooniverse on Vimeo.

now GO and get drawing!

(well done rob et al.!)

milky way's neighborhood

here is a lovely map of the close vicinity of our milky way galaxy, recently published in nature.  

click on this link to get a full-size version of the image and explore all the components.

our galaxy is a flat disk, consisting of spiral arms with billions of stars, gas, dust and some other stellar remnants.  from the southern hemisphere, you can see the dwarf galaxies, the magellanic clouds, with your naked eye on a clear night.   eventually these galaxies will interact more strongly with the milky way and become part of it.  this is what is happening to the sagittarius dwarf galaxy as revealed by observations of the sagittarius star stream.

all of this lives inside a huge spherical halo of dark matter.

nice neighborhood!

our home, the milky way

I've been searching for a good picture of our Galaxy, the Milky Way, for a couple years now and today the astronomy picture of the day provided the exact shot i saw in my mind!



thank you john p. gleason for your astrophotography!

this image doesnt seem like the classic galaxy picture you might have in your mind, swirling arms of speckled stars dancing around in a spiral twirl. that's because our earth is floating right next to one of those arms inside the big disk of the milky way. as you see in the picture below, we sit inside the pancake galaxy disk. When we look out in most directions, we see dark space with scattered star and distant galaxies. but when we look out thru the thick disk, we see the detailed arms of stars, gas and dust that you see in the image above.

all the light you see comes from stars like our sun shining brightly. the intensity of their light causes the clouds of gas glow! the dark patches are thick dust storms that block any light from passing through to our eyes and telescopes. The glowing red patches also reveal glowing gas, but this red version is all the same type: hydrogen!

milchstrasse

i admit, i like this observing gig! tonight is the last night of my 5-night official training run on the gemini-south telescope. i'm in charge tonight which is a bit daunting... so many things to remember on this complicated beast. luckily, it's partially cloudy. in general, moderately bad weather is the WORST type for observing because you constantly have to check for clouds and re-acquire guide stars and pause observations that are crappy, etc.... but for tonight it relieves the pressure a bit because i dont have to be as efficient as i would normally want. you have to be efficient when people tell you things like "this telescope costs $X to operate per second, so make every second count!" yikes!


overall, this observing run has been quite nice. despite the complication and stress of taking other people's data and trying to not break anything, it's really fun to run gigantic telescopes. since we're doing several different projects throughout the night, we look at things in our galactic neighborhood right before focusing on a galaxy as it was when the universe was only a couple billion years old!

and the night sky.... nothing soothes my soul like mountain vistas and hundreds of visible stars in the sky. the southern night sky has certainly lived up to all my expectations. the new moon denied us any of the sun's nighttime reflection just a few nights ago and it remains too dark outside to see my hand in front of my face. at first i can only see constellations that have quickly become familiar: the southern cross, upside-down orion, and of course the bright "evening star" venus... i cant recognize too many more southern constellations yet without the aid of a sky chart.


after a few minutes my eyes adjust to the darkness and more and more stars pop out of the blackness. i begin to see the elongated fuzzy patches that cross over the whole sky in a long straight line. i cant quite focus on all the elusive white speckles when i look directly at them, but what i see just off the center of my vision reinforces why our ancestors named it the great milky way. in german, they call it "milchstrasse" which translates to "milk street". what is the name of the milky way in spanish? "calle de leche"? anyone?

i love just going outside throughout the night and letting my eyes become acquainted with the immensity of space over and over again.

another fun aspect of the observing in chile is the food at the lodge! there are chilean chefs who cook meals for us each day. i work for about 14 hours a night this time of year and try to sleep for 7-8... so it's nice that they cook food i can eat! the food this week has been very good, but almost everyday there has been some food item offered that i couldnt identify. this isnt necessarily a bad thing, in fact it's kind of exciting! i've tried everything i've encountered so far (even the intestine that showed up on a grilled plate in La Serena last week. i had one tiny bite and i'll suffice it to say that i did not have another). one meat looked like a cornish game hen that had all the bones sucked out of it so it looked deflated then fried. it turned out to be chicken. there was one thing that i didnt ask about because the consistency was quite like tongue, and i thought it would be better not to know. there's always chilean salad which consists of tomatoes and onions in a bit of oil. i've also had some great desserts that contain lots of various fruits and syrups!

sometimes while observing i have a hard time sleeping a full 7 or 8 hours... due to the altitude, maybe? this run i've had no trouble at all sleeping, which must be due to some combination of the elevated stress level of such complicated observing all night long... and the fact that i've been eating soooooo much yummy food!!


UPDATE: this image, captured by miloslav druckmuller in argentina with the patagonias in the foreground, represents almost exactly what i saw when i first arrived in chile in january.

you can see the wonderful comet mcnaught in addition to the long stretch of the milky way. above the comet and a bit to the right you can see a little fuzzy smudge, and then another slightly larger smudge further up to the right. these are little irregular galaxies called the small and large magellanic clouds... only visible from the southern hemisphere!

the large magellanic cloud harbored the closest supernova in 400 years... supernova 1987a! all of us dorks celebrated the 20th anniversary of this spectacular stellar explosion on february 23rd. i tried to take more observations of the supernova last week, but the clouds prevented my success :(

Five things we know about the universe that will make you feel very small

Here is an article I contributed to ABC Science, originally posted here.

Five things we know about the universe that will make you feel very small.

One thing we know about the universe is that it's really big. Another is that thinking about it and trying to understand it will make your brain hurt.

Astronomer Amanda Bauer takes us through her top five mind-expanding things we know (or don't know) about the universe.

1. There is no edge of the universe

PHOTO: Full-sky map of the oldest light in the universe (NASA/WMAP Science Team)

There is one edge we know of - our horizon, which is the limit of how far we can see.

Imagine sailing on a boat on the ocean and seeing a horizon in the distance, past which you know there is more Earth, but you just can't see it. We've measured the universe to be flat (as opposed to curved like Earth or saddle-shaped), but our horizon exists because of the finite speed of light.

Beyond that visible horizon, we think the universe just keeps going in the same way - forever.

We have no reason to believe there is an edge. But we also have no way of measuring this infinity because we physically cannot see it.


2. Dark matter and dark energy make up 95 per cent of the universe

PHOTO: A composite image showing the galaxy cluster 1E 0657-56, better known as the bullet cluster. Gravitational lensing was used to locate the dark matter (shown as blue patches) in these two colliding galaxies. The pink colour shows gas blown apart by the collision. (NASA/Chandra X-Ray Observatory)

Only 5 per cent of the universe is made of ordinary material like planets, stars, cars, and coffee. This "normal matter" is made mostly of protons, neutrons, and electrons.

Another 24 per cent is an exotic material that interacts through gravity, but produces no light, making it invisible to us. We call this "dark matter".

While dark matter only interacts with normal matter very weakly, particle physicists have plausible candidates for what dark matter is.

Hopefully particle accelerators like the Large Hadron Collider will provide more insight for scientists very soon.

That brings us to the final 71 per cent of the stuff in the universe, which is a truly bizarre type of matter. Perhaps it's not matter at all, but a property of the universe itself. We call this mysterious stuff "dark energy".

What we do know is that dark energy has a gravitationally repulsive effect that is causing the expansion of the universe to speed up. But we don't understand how this acceleration is happening.


3. There is no centre of the universe

PHOTO: In a way, we're all at the centre of our own universe. (NASA/Ames/JPL-Caltech)

The universe has been expanding ever since the Big Bang 13.8 billion years ago.

But the Big Bang should not be imagined as a normal explosion in space. Rather, the Big Bang is an explosion of space itself, so that every point in space expands equally away from every other point in space. There is no centre to the expansion.

From our galaxy we measure that all galaxies are moving away from us, and the farther the galaxy, the faster away it is moving.

The interesting thing is that if you zoomed off to any other galaxy in the universe, you would measure the exact same effect - all other galaxies would be moving away from you.

In this way, you could argue that you are the centre of the universe. But then, so is everyone else.


4. Far-away galaxies offer a glimpse into the past

PHOTO: At 3 million light years from Earth, the Triangulum galaxy is even further away than Andromeda, so gives us a glimpse even further back in time. (NASA)

When we look at distant galaxies, we are actually looking at a snapshot of the past.

Some galaxies are located so far away their light takes billions of years to reach us, even travelling at the speed of light. The images we collect through our telescopes tell us what the galaxies looked like billions of years ago, when the light left the galaxy.

Andromeda is the nearest spiral galaxy to our Milky Way. It floats at a distance of 2.5 million light-years, so the views we capture of Andromeda show us what it looked liked 2.5 million years ago. And that's the closest spiral galaxy.

The farthest galaxy we have detected is 13 billion light years away. This means we are looking at galaxy light as it was only 2 billion years after the Big Bang.

We will never capture light from the future though, only the distant past.


5. The future will be dominated by black holes

PHOTO: Pretty much all galaxies have a supermassive black hole at their centre. This one, a spiral galaxy known as NGC 4258, also has two unusual spiral arms that glow in X-ray, shown in purple. (ASA/CXC/JPL-Caltech/STScI/NSF/NRAO/VLA)

We are currently in the Stelliferous Era - meaning the universe has a lot of stars. This era began a few hundred million years after the Big Bang when the very first stars formed.

Now, almost 13.7 billion years later, new stars continue to form, although the number of new stars forming each year is dropping.

Eventually, new stars will stop forming and all stars will slowly burn out. But in that very distant future, supermassive black holes will still thrive.

It's believed that nearly every galaxy in the universe has a supermassive black hole at its centre, which means that eventually hundreds of billions of supermassive black holes will be spread throughout our ever-expanding universe.

Over trillions and trillions and trillions, and many more trillions, of years these black holes will slowly evaporate through Hawking Radiation.

The leftover elementary particles will be left to zoom through a vast, cold space with nothing much around to bump into.

Sounds very empty.

collecting SAMI galaxies

I've been up at Siding Spring Observatory visiting this beauty this week.

The dome of the 4-metre Anglo-Australian Telescope

I enjoy walking around the dome's catwalk to see the views in all directions.

Hello from the catwalk!

 The first night provided a lovely (cloudy) sunset.

But then the skies cleared BEAUTIFULLY for most of the observing run and the Milky Way glowed brilliantly across the early evening sky.

We have been using the SAMI instrument during this run to observe over 100 galaxies so far!

Perched at Prime Focus with SAMI

Kristin was the telescope operator for the beginning of the run. Here she is with the original control panel that was installed 40 years ago!  while it still looks roughly the same - systems and displays have been upgraded over the years :)

we had some time for enjoying the clear night skies while exposing with the big telescope

The Magellanic Clouds and the AAT dome. (Credit: Jesse van de Sande)

Milky Way (Credit: Angel Lopez-Sanchez)

And we may have started to write a few songs for "SAMI - then Musical"  ;)

GLOBE at night - observe orion!

the 94th carnival of space led me to an article by the space writer asking: are your skies dark? i feel like i can see fewer and fewer stars with my eyes in the night sky, and that's not *just* because my eyes are aging or because i recently moved to the cloudy UK! most people on earth live in cities and most cities are completely lit up at night, as you can see in the image below of the earth at night!


a few years ago, i asked a class of 200 university students how many had seen the milky way across the night sky. not even half of them raised their hands! i admit that i didnt see the milky way in the sky until i was 19 and camping in the mountains of california. the sighting coincided with the year i switched my undergraduate major to physics.

in an effort to promote getting out and observing the night skies, the GLOBE at night project begins this week! the main activity is for people all over the world (you!) to go outside and look at the constellation orion between 16-28 March 2009. orion is one of the fun constellations that is visible from both hemispheres, but looks upside down when you visit the other hemisphere!


the GLOBE at night website provides nice explanations as to how to find orion from anywhere in the world, but it's definitely one the most recognizable constellations in the sky.

after you identify orion, you can continue participating in the project by comparing the nighttime sky you see with the GLOBE's magnitude charts, to see how dark your night sky is! you can then record your observations on their website until april 7th, 2009 and compare how dark your skies are to the rest of the world!

orion is up early right now, about 7-10pm local time. happy observing!

... and let us know if you find any exciting or unexpected results!

from here to infinity

I'm out at siding spring observatory for the next week.

never underestimate the power of duct ("gaffer") tape!

a stunningly bright planetary pair slowly peaks out of the darkening sky, as pale blue fades through sunset colors to deep black.

venus and jupiter are on show for an hour, then i have to retreat inside to work.

when i emerge again outside on the catwalk surrounding the telescope dome, the deep black darkness shocks my eyes. the moon has not yet risen and the current solar system show-offs have already set.

orion sits upside down while the southern cross reaches around the milky way. our galaxy begins to shoot across the sky and the two magellanic clouds shyly tag along for the ride.

i find mars quite easily in the eastern skies and notice my surprise at just how obviously red its reflected sunlight glows!

as my eyes dark-adapt, fainter dots begin to speckle the sky. i start to lose the three stars of orion's belt amidst the incredible number of stars. so many stars!

and these are just the stars i can see with my eyes, our solar neighborhood, a tiny fraction of all the stars that make up our milky way galaxy.

and there are billions and billions of galaxies in the universe! so. much. space.

and then it's that moment again, BAM! a swell of intensity, overwhelmed and slightly dizzy, as i realize just how big the universe is.

wow.

and just as quickly, i'm back on earth, looking at the solid black silhouette of our home planet stretching softly out to the horizon, where it touches the star-filled sky.

i love those moments.



for more of what's happening overhead right now at siding spring, check out show me stars!

dirty space news: solid as a rock

this earthly spire is excitedly reaching toward the milky way galaxy in today's dirty space news entry. the rock formation, called castildetierra, is located in bardenas reales, spain.  

Photo Credit: Maria Rosa Vila

why does the milky way arc like a rainbow across the sky in this photo, you might be wondering?  the image is a collection of 14 different shots that were added together for the final effect.  the photographer would have stood in a single place and taken photos in all directions to capture images of the entire sky. then she added them together and cropped the final image in post-processing.

i think the lack of any distortion in the final combined image is impressive! or maybe the universe is just naturally attracted to that 50 meter pillar of stiff rock ;)

comet siding spring and mars

Comet C/2013 A1 (Siding Spring) will pass within 139,500 km (86,000 miles) of the surface of Mars at 5:51 tomorrow morning (Monday 20 Oct, Sydney time - or 19 October at 18:51 UTC).  This means Comet Siding Spring will pass 10 times closer to Mars than any (recorded) comet has flown by Earth!  But it will be traveling at 50 km/s which is too fast to be captured by Mars's gravitational pull.

Comet Siding Spring was discovered by Rob NcNaught at Siding Spring Observatory in New South Wales on 3 January 2013.  Last night Steve Lee took this beautiful image of Comet Siding Spring and Mars against the dusty backdrop of the Milky Way using a 90mm refractor and Canon 6D camera, from a location VERY CLOSE to siding spring observatory!

Comet Siding Spring, Mars, and Milky Way dust (Photo by Steve Lee (AAO))

 
The comet is still composed of the pristine material the solar system was made from, which will give insights into the formation of planets!

more info about the comet from Dr bruce betts:



For a list of ways to view the comet (if you dont have your own telescope or are covered in clouds), see The Planetary Society blog by the great Emily Lakdawalla here. 

milky way reflection

i found more really great astronomy photographers: tony and daphne hallas at astrophoto.com



the image below shows the galaxy, M63, as featured on APOD today. this galaxy is about the same size as our Milky Way at 100,000 light years across. It floats about 25 million light-years away from us and is known as the sunflower galaxy. you can easily see the blue spiral arm structure, but the most amazing parts of the image, i think, are the faint wisps of structure around the outskirts of the galaxy! it's difficult to se these very dim features in most images! they show what are probably streams of dust and gas left over when smaller galaxies came within close range of the sunflower. gravitational interactions can cause such distortions in galaxies when they pass by each other and eventually merge together into one.

supernova calling

roughly one supernova explodes in a galaxy every one hundred years.

telescopes scan the sky regularly for changes which could reveal objects like asteroids moving quickly across space or stars exploding as supernova in distant galaxies.  even with advanced technology, sometimes the automatic telescopes miss things, and a supernova that exploded in nearby galaxy M82 yesterday is one such example!

it turns out an astronomy class at the university of london observatory were imaging M82 and noticed a bright spot that didnt look familiar!

here is a before (top) and after (bottom) shot showing the bright supernova in the dusty spiral galaxy viewed from its side.

The supernova in M82

Credit: UCL/University of London Observatory/Steve Fossey/Ben Cooke/Guy Pollack/Matthew Wilde/Thomas Wright

This supernova appears to be a Type 1a, meaning it was a white dwarf star that gravitationally pulled in enough gas from a neighbouring star, that it became too dense and exploded.  precisely how this happens is still a mystery, which is one of the many reasons why this relatively close explosion is so exciting!

The M81-M82 galaxy pair live in Ursa Major near the Big Dipper.
Credit: Sky and Telescope. 

if you live in the northern hemisphere, get your binoculars ready! the light from this stellar explosion has been traveling to us for 115 million years, and it hasnt reached its peak brightness yet!  so iver the next two weeks, have a look with binoculars or telescopes and try to spot the it! 

galaxies M81 (left) and M82 (right) through the milky way's haze (Credit: Ivan Eder)

here's a lovely image of M81 and M82 from APOD last year.  the fuzzy stuff that appears to be floating the space in the image is not associated with those galaxies at all.   after exposing for 25 hours, the photographer managed to capture the faint glow of the cirrus dust clouds in our own milky way galaxy.   beautiful!