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Milky Way’s neighbouring galaxy is of same size, not bigger

With Andromeda no longer considered the Milky Way's big brother

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Countless galaxies exist in the universe, each hiding secrets that humankind is yet to unearth. Pixabay
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  • Astronomers discover that the other galaxy nearest to us is the same size as ours
  • The name of the other galaxy is Andromeda
  • It is heavier than sun but the same size as Milky Way

In what could put a galactic arms race to rest, astronomers have discovered that our nearest big neighbour, the Andromeda galaxy, is roughly the same size as the Milky Way.

It had been thought that Andromeda was two to three times the size of the Milky Way, and that our own galaxy would ultimately be engulfed by our bigger neighbour.

Galaxy nearest to Milky Way is not larger than it. VOA
Galaxy nearest to Milky Way is not larger than it. VOA

But the new study, published in the journal Monthly Notices of the Royal Astronomical Society, evens the score between the two galaxies.

It found the weight of the Andromeda is 800 billion times heavier than the Sun, on par with the Milky Way.

The research suggests scientists previously overestimated the amount of dark matter in the Andromeda galaxy.

Also Read: Planets Beyond Milky Way Galaxy Discovered For First Time

“We had thought there was one biggest galaxy and our own Milky Way was slightly smaller but that scenario has now completely changed,” said Prajwal Kafle from the University of Western Australia.

“By examining the orbits of high speed stars, we discovered that this galaxy has far less dark matter than previously thought, and only a third of that uncovered in previous observations,” he said.

Andromeda  is heavier than sun. VOA
Andromeda is heavier than sun. VOA

The study used a new technique to measure the speed required to escape a galaxy.

“When a rocket is launched into space, it is thrown out with a speed of 11 km per second to overcome the Earth’s gravitational pull,” he said.

“Our home galaxy, the Milky Way, is over a trillion times heavier than our tiny planet Earth so to escape its gravitational pull we have to launch with a speed of 550km/s,” Kafle said.

Andromeda is same size as the Milky way galaxy. Wikimedia Commons
Andromeda is same size as the Milky way galaxy. Wikimedia Commons

“We used this technique to tie down the mass of Andromeda,” he added.

The Milky Way and Andromeda are two giant spiral galaxies in our local Universe, and light takes a cosmologically tiny two million years to get between them.

With Andromeda no longer considered the Milky Way’s big brother, new simulations are needed to find out what will happen when the two galaxies eventually collide, suggests the study.

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STUDY: Lakes on Mars dried up 3.5bn years ago

A study reveals that lakes on Mars dried up 3.5bn years ago.

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An image of Mars.
Mars. Pixabay

The discovery of cracks on the surface of Mars by NASA’s Curiosity rover in early 2017 are evidence of lakes that likely dried up 3.5 billion years ago, confirmed a study, revealing details about the red planet’s ancient climate.

In early 2017 scientists announced the discovery of possible desiccation cracks in Gale Crater, which was filled by lakes 3.5 billion years ago.

“We are now confident that these are mudcracks,” said lead author Nathaniel Stein, a geologist at the California Institute of Technology in Pasadena, US.

Since desiccation mudcracks form only where wet sediment is exposed to air, their position closer to the centre of the lake bed rather than the edge also suggests that lake levels rose and fell dramatically over time.

“The mudcracks show that the lakes in Gale Crater had gone through the same type of cycles that we see on Earth,” Stein added.

Representational image for planet Mars.
Representational image. Pixabay

Although scientists have known almost since the moment Curiosity landed in 2012 that Gale Crater once contained lakes, “the mudcracks are exciting because they add context to our understanding of this ancient lacustrine system”, Stein explained, in the paper published in the journal Geology.

“We are capturing a moment in time. This research is just a chapter in a story that Curiosity has been building since the beginning of its mission,” he said.

Also Read: SpaceX to build Mars rockets in Los Angeles

For the study, the team focused on a coffee table-sized slab of rock nicknamed “Old Soaker”.

Old Soaker is crisscrossed with polygons identical in appearance to desiccation features on Earth.

They found that the polygons — confined to a single layer of rock and with sediment filling the cracks between them — formed from exposure to air, rather than other mechanisms such as thermal or hydraulic fracturing, the researchers said.  IANS