Five Astronomy Events You Want to Live Long Enough to Witness

Every now and then, we are bombarded with articles on the next big super-blood-wolf-moon happening that you do not want to miss, or listicles on astronomical events in the coming year or so. Meteor showers – the Geminids and the Leonids – happen regularly. Lunar eclipses are ubiquitous; solar eclipses less so, but often more spectacular. Comets, which you can see with the naked eye, come to visit the inner solar system once every few years, and then there are planetary conjunctions and transits across the face of the Sun. 

These events will occur aplenty in a human lifetime. Yet, there are some astronomical events for which the currently short human lifetime is not enough, and you would want to live a really long life to experience some of these events which will dazzle your mind.

1. Betelgeuse Goes Supernova

A supernova is a star-explosion, one of the brightest events in the Universe, and a single supernova outshines the light from entire galaxies containing 100 billion stars. When big stars run out of hydrogen to burn, their cores start fusing heavier elements up to iron, beyond which they cannot fuse. When the fusion stops, there’s nothing to push against the self-gravitation. The core of the star then collapses to form a neutron star or black hole, while blowing off the outer layers in a cataclysmic event called supernova.

In a galaxy like the Milky Way, a supernova happens about once every century. The most recent bright supernova which was visible to the naked eye was SN 1987A, located in the Large Magellanic Cloud, outside our galaxy, about 168,000 light years away.

The nearest star that could explode is Betelgeuse, a red supergiant star in the Orion constellation, only 640 light years away. Betelgeuse is the ninth brightest star in the night sky, and one of the most studied. It is less than 10 million years old and has lived its life very rapidly, astronomically speaking. It could blow up at any moment in next 1 million years. You won’t need a telescope to see it: it will not only be visible to the naked eye during the day, but also, it will be brighter than the full moon, and will be visible for several weeks before fading.

Artist’s version of Betelgeuse. Source: ESO/L. Calçada – http://www.eso.org/public/images/eso0927d/

2. Mars gets a ring

All big gas giant planets in our solar system have rings. Everybody knows about Saturn’s rings, but that even Jupiter, Uranus and Neptune have rings made up of water ice, grains of rock and dust, is little known.  

Live long enough and you might be lucky enough to witness Mars getting its own rings! The planet has two moons, Phobos and Deimos. Phobos, the larger of the two, is actually spiralling in towards the Red Planet, and will drop into the Martian atmosphere in about 20 to 40 million years. When it gets too close to the planet, the tidal forces on Mars (similar to those from our Moon which result in sea tides) would be so strong that they will break the moon apart into millions of pieces, large and small. The smaller pieces will gather into a set of rings, while the larger pieces would crash onto planetary surface. The rings won’t be permanent and would last only for several million years, but they would certainly be a fantastic view for future visitors to Mars.

Source: Nature Geoscience / B. Black & T. Mittal

3. Andromeda smashes into the Milky Way

A massive cosmic crash is coming, and you want to get ready for it! Our Milky Way is headed towards our big neighbour, the Andromeda galaxy at a whopping speed of 4,00,000 kilometres per hour! However, astronomical distances are so large that it will take the two galaxies another 4 billion years to tangle into each other. Andromeda, also known as देवयानी in the Indian context, is 25,00,000 light years away, so it looks very dim, just like a tiny smudge, in the night sky. But if it were as bright as we see it in the telescopes, it would appear six time as big as the full Moon!

 
How Andromeda galaxy would look like today, if it was brighter.  Source: www.reddit.com

The night sky would look truly spectacular as the galaxies get very close. Their collision would change our night sky forever as we see the Andromeda entangle with the band of the Milky Way. This crash will lead to massive star formation in both galaxies, though individual stars will not collide with each other. The two galaxies will take multiple passes at each other until eventually, they will merge together to form a single elliptical galaxy, currently nicknamed Milkomeda (we astronomers are very creative with the names).

View of the night sky in 5 billion years. Source: NASA, ESA, Z. Levay and R. van der Marel (STScI), T. Hallas, and A. Mellinger

4. Sun engulfs the Earth

There won’t be much time to enjoy this view of colliding galaxies from the Earth. Our Sun will eventually destroy our home. Sun, at 5 billion years old, is a middle aged, main-sequence star. In another 5 billion years, it will run out of hydrogen to burn, and enter the phase of a red-giant, during which its core will collapse under its own weight while the outer layers expand. The Sun will grow in size to engulf Mercury and Venus, and possibly the Earth too. Even if it doesn’t consume the Earth, it will have become so big that it will bake the surface of our planet, boil all the oceans, and even change the Earth’s orbit. All life present on Earth would go extinct or will have to move to outer planets or other stars.

Source: NASA/SDO

5. End of the Universe

Eventually all stars will run out of fuel. Even the stellar remnants, neutron stars & black holes will ultimately evaporate & fade, in a googol (10 to the power 100, or 1 followed by 100 zeros) years. The Universe will keep moving apart, with ever-accelerating expansion. It will slowly isolate all galaxies which are left over until even matter is torn away, moving everything away from us beyond the horizon from which no light will reach us. Nothing physical that makes us will survive this, but hopefully we will have already found a way to live a non-corporeal life. The end is devoid of all structure, each point alone in the volume of universe, with only stray radiation passing around and no way to extract energy. This is the “heat-death of the Universe”. Yet, may be, after an eternity or few, we might get a fresh start!

Dr Abhijeet Borkar

Dr Abhijeet Borkar is an Astrophysicist and a Postdoctoral researcher at the Astronomy Institute of the Czech Academy of Sciences, Prague, Czech Republic. 

The views and opinions expressed in the article are those of the authors and do not necessarily reflect the official policy or position of The Tilak Chronicle and TTC Media Pvt Ltd.

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