We know for example that our galaxy the Milky Way, and our sister galaxy Andromeda, are on a collision course with each other. It won’t be a collision in the sense of planets and stars smashing into each other, the spaces between these bodies are so vast that almost nothing will actually hit anything else, it will be more of a merging of the galaxies. The most probable outcome is that the entire solar system will be violently ejected from the newly formed ‘supergalaxy’. This is about 4 billion years hence.
If the Sun manages to survive it won’t be long after that before it destroys itself. At present it is a truly immense ball of matter that is burning up in one colossal nuclear reaction. In time the mass will decrease and the star will collapse in on itself before expanding outward. It will not, as popular myth believes, be a supernova; but it will spell the end of the Earth if it’s not already been destroyed. This will happen in about 5 billion years time.
We have another problem with our galaxy in that there’s a supermassive black hole lurking in the centre of it, this is called Sagittarius A and it has a mass equivalent to about 3.6 million of our Suns. We know that mass equals gravity so the gravitational pull of this black hole is phenomenal. It’s a bit unfortunate as Andromeda also has a supermassive black hole and this one is even bigger. As the two galaxies draw together it’s possible Earth would be ‘sucked into’ one of the black holes.
Then of course there’s the fact that Earth lies in a cosmic firing range with bits of meteors and asteroids shooting across the solar system. We get hit by these all the time but most are small and burn up due to the friction of the atmosphere. Occasionally a large one makes it through and impacts with the Earth. Depending what size the bolide is determines how much damage is done.
It was one such asteroid collision that wiped out most dinosaurs and other species that were alive some 66 million years ago. This particular one hit just off the coast of the Yucatan Peninsular. It wasn’t so much the impact that was the problem, more the fact that it exploded into tiny fragments and threw vast quantities of dust and debris into the atmosphere, so much in fact that it blocked out the Sun and the entire planet cooled by about 4°C. The effect was enough to kill most plants and usher in a period of rapid glaciation. Such an event could happen any time, we could have as little as a few months notice or many years. Such events are rare, happening once in every tens of millions of years so it’s unlikely to happen whilst humans are on the planet.
We could get hit by a protoplanet, this really would be catastrophic. It probably happened before. Earth used to have a twin called Theia, it was smaller than Earth at roughly the same size as Mars. Some 4? billion years ago when Earth was newly formed, Theia smashed into Earth at a speed of about 14,000 kmh. The resulting collision destroyed Theia with parts of it being hurled into space and other parts being accreted into Earth. Much of Earth’s mantle was torn apart and thrown into space. The space debris from both planets quickly coalesced through gravity and the result is the Moon. This is another unlikely scenario but given the delicate balance that holds planets in place, it’s not impossible for it to happen again.
Even the universe itself is finite. Despite the fact that it is of truly immense proportions it is already falling apart. Everything that makes up the universe already exists, everything that you are made up of existed long before you were born. In fact, whilst it may sound like something a hippy would say, we are all actually made up of star dust. All that happens is that objects decay and the atoms and molecules they were made of go toward making something else.
There is no new material available in the universe but the existing material is very, very slowly being lost to entropy. In a staggeringly long period of time (90 novemvigintillion years from now) there will be no universe.
Ice-ages are a problem for life on Earth, not the small ones that come and go every 95,000 years but the really big ones, the true ice ages. These are the ones that freeze almost the entire planet, leaving only a band round the Equator free of ice. We’re heading toward the next one but the peak is still some 50 million years away.
These ice-ages are related to the way that the entire solar system orbits the galactic centre. Our galaxy has spiral arms radiating out from a central bar, it’s these arms that are the densest and have significant amounts of cosmic radiation, this keeps the arms warm. The vast empty spaces between the arms are much cooler and that’s where we’re heading now.
About 630 million years ago the entire planet froze solid, we’re not quite sure why that happened, probably because the amount of greenhouse gas in the atmosphere was particularly low and this coincided with the peak of an ice-age. It would have been cold anyway but other factors made this ice-age especially cold. Thankfully a few million years of increased volcanic activity created enough carbon dioxide gas to restart the greenhouse effect and the planet eventually emerged from it’s icy slumber.
On a more human timescale we have many other things that could happen to us.
For example, only 73,000 years ago, or thereabouts, humanity was almost wiped out by a supervolcano. This was the Indonesian volcano Toba, it was the equivalent of hundreds of Krakatoas going off at the same time and was the largest explosion on Earth since the Oxaya Ignimbrites eruption about 20 million years earlier.
It is now thought that Toba wiped out all be a few thousand humans with most of the survivors being in Southern Africa and perhaps some in Southern India as well.
The eruption caused a nuclear winter that lasted up to 10 years and ushered in a period of global cooling that lasted up to 1,000 years.
We also have the smaller ice-ages to contend with, the ones that happen at 95,000 year intervals. They’re more correctly called glacials or periods of glaciation and are caused by changes in the shape of Earth’s orbit around the Sun. These are regular changes so the glacial periods are easy to predict.
We’ve just come out of one, a mere 10,000 years ago, and are now heading toward the next glacial, the peak of which will happen in about 73,000 years. If humans are around then there will need to be mass migration as half of the northern hemisphere will become uninhabitable. It won’t kill off the human race but it will make life very difficult.
There are loads of other things that can happen but I think I’m going to run out of space soon.
The important thing to remember is, that whilst there are many potential extinction level events, they are few and far between. Such an event could happen any time now or not for millions of years. Statistically the odds of such an event affecting anyone alive today is extremely small.
Sagebrush --
Is that the same heavenly father who says that we should practice gay sex while smoking marijuana?
Leviticus (20:13) “If a man lies with a man as he would with a woman, they should both be stoned.”.
Our heavenly Creator has told us that it will ALWAYS be livable.
Eccl. 1:4 One generation passeth away, and another generation cometh: but the earth abideth for ever. KJV
After that promise, who would listen to mortal man?
Gary F: Good one! However, I think something got lost in your translation as to the real intent.
They haven't, because there's still many many millions of years left, which can be altered by the size of our carbon footprint.
Forecasting the future is fraught with dangers, but seeing as life started around 540million years ago in the Cambrian period, I expect we have many more millions, if not billions of years left.
Earth has billions of years before sun swells into a red
giant . give or take a 100 years
The weather today is like it was before Global Warming, so everything is back to normal like it was in the 1970's. Our Satelite reports Ice is again accumulating on different parts of earth, since GLOBAL WARMING ENDED IN 2012. Global Command
