The Earth is closer to Milky Way’s supermassive black hole than we thought4 min readReading Time: 3 minutes
All Things Science
The earth is part of the galaxy, Milky Way. At the centre of the galaxy, rests a super massive blackhole called Sagittarius A*. It is called supermassive because it is a billion times more massive than the sun! A blackhole is a place in space where the pull of gravity is so strong that even light cannot escape it.
Do you remember the story of the shimmying blackhole, M87?
New research has revealed that our home planet is 2,000 light years closer to the Milky Way’s supermassive black hole than the previous estimate. Earlier, the distance was recorded at 27,000 light years. A 15-year analysis through Japanese radio astronomy project VERA has now placed that distance at 25,800 light years.
Owliver’s Obscure Observations:
What is a light year?
Objects in space are extremely far from us. So, while we can measure the distance from our homes to our friend’s house in kilometres, it is impossible to do that for celestial objects like stars, planets etc. Imagine having to calculate distance and time for 1000 trillion kilometres! So, we use a separate measure of distance that is light years.
Light year is the distance travelled by light through empty space in a year.
If a star is 1000 light years away from us, its light will take 1000 years to reach us on earth. So, when we actually get to ‘see’ the star through the travelled light, the position of the star may have changed over the course of the 1000 years. So, what we are seeing is the light of the star from 1000 years ago from that position and not the star itself!
Isn’t that fascinating? Almost magical.
Learn more about light years in the video below-
Apart from the closeness between earth and the blackhole, the new research also reveals that earth is moving 7km/s faster than previously believed.
So, why are we not worried?
The answer is simple. This discovery does not reveal a change in the way earth was meant to move but indicates a more accurate model of the galaxy.
We know more now than we did before!
We are not moving towards the blackhole but now, we know where we stand in relation to it in the galaxy. Thanks to the VERA Astrometry Catalog, scientists have been able to create a map that shows the objects that reside within the galaxy, the centre of the galaxy, and their relational position.
How did VERA manage it?
VERA stands for VLBI (Very Long Baseline Interferometry) Exploration of Radio Astrometry. There are two operative words, here- Interferometry and Astrometry. They look big but they have simpler meanings.
Interferometry measures disturbances and interferences in how light travels.
And Astrometry measures the distance a certain object has from another object in relation to others around them. Since, earth orbits around the sun, the distances between earth and its celestial friends are not constant. So scientists use a method called parallax to measure such a distance.
Parallax is the perceived change in position of an object seen from two different places.
Owliver’s Obscure Observations:
Why are we so concerned with Earth’s long distance relationships?
Since earth is situated inside the galaxy, it is hard to understand what it looks like from the outside. Here, astrometry has helped convey earth’s position to curious earthlings.
The first VERA Astrometry Catalog was published this year. It includes data for 99 objects. VERA has been collecting data over 15 years to give an accurate image of where we lie in this galaxy!
And it will continue to lend more accuracy to previous judgements revealing more about the magical universe and our position in its spell.
Tonight, before going to bed, look out your bedroom window and try to find some stars in the night sky.
For all you know, you may be ‘seeing’ a star that has already exploded millions of years ago. But its light is still reaching you to make you believe in wonder.
Remember the pale blue dot and let go of any mid-week stress!
(All Things Science is weekly column about science, space and other things around it.)