Milky Way galaxy heading for a collision – in about 4,000,000,000 years!
As with huge numbers of others who come to this blog, the night sky has always been of incredible fascination to me. To reinforce that fact, one of the favourite posts on Learning from Dogs for the last three years has been The night sky above published back on the 27th March, 2011. If you haven’t read it, do pop across and do so as the title is misleading in terms of the post.
As seen on Cosmos … the collision and merger between our Milky Way galaxy and the nearby Andromeda galaxy 4 billion years from now.
The video below illustrates what NASA scientists announced in 2012 – and what the Cosmos TV series featured in 2014 – that the nearby Andromeda galaxy will collide and merge with our Milky Way galaxy 4 billion years from now. The video (from the Hubble Space Telescope news center) is from a series of photo illustrations, showing the predicted merger between our two titan spiral galaxies, as seen in Earth’s sky. Will Earth as a planet survive long enough to see this? A word about that at the end of this post.
The video lost a lot for me by not carrying a commentary. But no problem as one was found that did have a ‘voice-over’. However, the article photographs were stunning. For example:
This series of photo illustrations shows the predicted merger between our Milky Way galaxy and the neighboring Andromeda galaxy. Via NASA; ESA; Z. Levay and R. van der Marel, STScI; T. Hallas, and A. Mellinger
A description of what’s happening in the images above:
First Row, Left: Present day.
First Row, Right: In 2 billion years the disk of the approaching Andromeda galaxy is noticeably larger.
Second Row, Left: In 3.75 billion years Andromeda fills the field of view.
Second Row, Right: In 3.85 billion years the sky is ablaze with new star formation.
Third Row, Left: In 3.9 billion years, star formation continues.
Third Row, Right: In 4 billion years Andromeda is tidally stretched and the Milky Way becomes warped.
Fourth Row, Left: In 5.1 billion years the cores of the Milky Way and Andromeda appear as a pair of bright lobes.
Fourth Row, Right: In 7 billion years the merged galaxies form a huge elliptical galaxy, its bright core dominating the nighttime sky.
The sequence is inspired by dynamical computer modeling of the inevitable future collision between the two galaxies.
Further on in the article one reads:
This illustration shows the collision paths of our Milky Way galaxy and the Andromeda galaxy. The galaxies are moving toward each other under the inexorable pull of gravity between them. Also shown is a smaller galaxy, Triangulum, which may be part of the smashup. Via NASA; ESA; A. Feild and R. van der Marel, STScI.
Will Earth survive long enough to see this merger of galaxies, as depicted in the video above? Earth as a planet might, but life on Earth – probably not. Astronomers say that the luminosity, or intrinsic brightness, of our sun will steadily increase over the next 4 billion years. As the sun’s luminosity increases, the amount of solar radiation reaching the Earth will also increase. It’s possible that – around 4 billion years from now – the increase in the Earth’s surface temperature will cause a runaway greenhouse effect, perhaps similar to that going on now on the planet next door, Venus, whose surface is hot enough to melt lead. No one expects to find life on Venus. Likewise, life on Earth will probably not exist 4 billion years from now. What’s more, our sun is expected to become a red giant star eventually. A probable fate of the Earth is absorption by the sun in about 7.5 billion years, after our sun has entered the red giant phase and expanded to cross Earth’s current orbit.
Anyhow, I mentioned that I found a better video on YouTube than the one included in the original article, and that is now presented.
Rather puts the grunt and grind of daily life into perspective! 😉
The immensity of the universe and what it means for Planet Earth.
Jean and I have been watching the astounding BBC Series Wonders of Life presented by Professor Brian Cox. Here’s the BBC trailer:
and there are more clips from the programmes on the relevant part of the BBC website. There is so much about the series that is breath-taking. So much that reminds one of what a beautiful and fragile planet we live on. Quite rightly, the series received great reviews. Here, for example, is a little of what the UK Daily Telegraph newspaper wrote:
Wonders of Life, BBC Two, review
Sarah Crompton reviews the first episode of Brian Cox’s latest series, Wonders of Life (BBC Two).
When it comes to presenting styles, Professor Brian Cox is hard to keep still. There isn’t a beach he won’t feel compelled to stroll on, a mountain he won’t climb, or a river he won’t jump into. And what does he carry in that bag?
Once you got beyond these irritating stylistic tropes, however, Wonders of Life (BBC Two) was Cox at his absolute best, using his natural enthusiasm to communicate complicated ideas in very simple ways. He decided, for example, to show us his own DNA by spitting in a test tube – and missed.
“A physicist doing an experiment,” he giggled, with unforced charm. But when he actually succeeded, those little strands of white that you suddenly see brought everything he subsequently said to life.
He was brilliant at explaining his thesis, which was actually about the second law of thermodynamics, so not that much of a doddle to grasp. If I’ve got it right, what Cox thinks is that life itself may have been the inevitable consequence of the laws of physics and can be explained in the same terms as we explain “the falling of the rain and the shining of the stars”.
Sarah rounds off her review, thus:
The programme’s sophisticated use of graphics, and Cox’s patient repetition of his conclusions, all added to the sensation that this is a series that is actually going to tell you something. For the BBC to unveil both this and The Story of Music over a single weekend reveals a pretty impressive commitment to public service broadcasting. Long may it last.
One of the clear messages that comes from the program is the fact that our universe and the formation of life are intimately connected. That the ‘big bang’ some 3.2 billion years ago, the huge interstellar gas clouds, the formation of the carbon atom and the subsequent long-chained molecules, the collapse of those gas clouds to form suns and planets, the start of life, evolution through natural selection to ever more complex life forms, and on and on and on were and are inevitable. The science is clear. There is nothing mystical about it.
Yes, of course, anyone with half-an-ounce of sensitivity will be in awe of it all; the power and beauty of nature and of the natural world.
But here’s the rub.
As another BBC television programme explained, the universe is bigger than beyond imagination. That was from the BBC Horizon broadcast of August, 2012: How Big is the Universe? Here’s the trailer for that programme.
Stay with me a little longer! Just look at the following image.
The Andromeda galaxy.
This image of the Andromeda galaxy, taken in infrared and X-ray, consists of over a trillion stars.
The detailed Spitzer Space Telescope view above features infrared light from dust (red) and old stars (blue) in Andromeda, a massive spiral galaxy a mere 2.5 million light-years away. In fact, with over twice the diameter of our own Milky Way, Andromeda is the largest nearby galaxy. Andromeda’s population of bright young stars define its sweeping spiral arms in visible light images, but here the infrared view clearly follows the lumpy dust lanes heated by the young stars as they wind even closer to the galaxy’s core. Constructed to explore Andromeda’s infrared brightness and stellar populations, the full mosaic image is composed of about 3,000 individual frames. Two smaller companion galaxies, NGC 205 (below) and M32 (above) are also included in the combined fields. The data confirm that Andromeda (aka M31) houses around 1 trillion stars, compared to 4 hundred billion for the Milky Way.
Please stay with me for a few more minutes. Keeping the Andromeda galaxy in mind, now read this:
ESA astronomers say that for every ten far galaxies observed, a hundred go undetected.
Astronomers estimate that there are between 100 billion and 200 billion galaxies in the known universe. A single galaxy such as the Milky Way contain upwards of 200 billion normal stars. About 75 percent of all stars in the Milky Way are less than half as massive as our Sun. In the universe at large, the majority of galaxies are classified as dwarfs, each with less than a few hundred million stars. The image above is a computer simulation of a colliding dwarf galaxy triggering the formation of the Milky Ways spiral arms.
The largest project ever undertaken to map out the Universe in three dimensions using ESO telescopes has reached the halfway stage. An international team of astronomers has used the VIMOS instrument on the ESO Very Large Telescope to measure the distances to 55,000 galaxies as part of the VIPERS survey (VIMOS Public Extragalactic Redshift Survey). This has already allowed them to create a remarkable three-dimensional view of how galaxies were distributed in space in the younger Universe.This reveals the complex web of the large-scale structure of the Universe in great detail. The light of each galaxy is spread out into its component colours within VIMOS. Follow up analysis then allows astronomers to work out how fast the galaxy appears to move away from us — its redshift. This in turn reveals its distance and, when combined with its position on the sky, its location in the Universe.
Wow!
Millions of galaxies, trillions of suns, inconceivable numbers of planets.
Please pause and let the numbers sink in.
Now back to that Wonders of Life BBC series, during which Professor Brian Cox, said, “that it is inconceivable that there isn’t life elsewhere, that life is not present on countless other planets circling countless other suns …“.
In other words, if mankind is so intent on ‘fouling our nest’ on this most beautiful of planets, so what!
In the bigger scheme of things, it matters not. Find that tough? Then go and hug a dog and enjoy the moment. For tomorrow may never come.
Learning from Dogs 