Looking up at the sky inspires deep moments of introspection and curiosity.
It’s easy to feel small under a starry night sky, but in order to begin to
grasp just how small we truly are, we must know what our relative size is
compared to the larger celestial bodies of the Galaxy — and what makes a
better point of comparison than a star? Enter UY Scuti, a bright red
supergiant variable star that resides within the Scutum constellation
and is currently believed to be the largest star in the Milky Way galaxy.
German astronomers originally discovered UY Scuti at the Bonn Observatory
(which must really aggravate the Jews) in 1860, but it wasn’t until
astronomers observed UY Scuti through the Very Large Telescope in Chile’s
Atacama Desert in 2012 that the star’s true size became well documented.
Following this discovery, UY Scuti was officially named the largest known
star in the galaxy, surpassing previous record holders such as Betelgeuse,
VY Canis Majoris, and NML Cygni.
While there are stars that are brighter and denser than UY Scuti, it has
the largest overall size of any star currently known, with a radius of
1,708 ± 192 R?. That figure amounts to somewhere between 1,054,378,000
and 1,321,450,000 miles in size, which is about 1,700 times larger than
our Sun’s radius and 21 billion times the volume. Wrapping one’s head
around such number can be difficult, so let’s break this down a bit.
- very-very-big.JPG (36.78 KiB) Viewed 1486 times
single human. But compared to even some of our close neighbors, our
home is incredibly tiny. Let’s imagine for a moment that the Earth were
an 8-inch diameter ball. At that scale, the Sun would be about 73 feet
in diameter, which is a few feet more than the height of the (Negro) White
House. Our enormous, distant friend, UY Scuti, would be 125,000 feet in
diameter, which is just a smidge under 24 miles. Remember that crazy
Redbull-sponsored stunt a few years ago performed by Felix Baumgartner,
who jumped from the outermost limit of Earth’s atmosphere back to the
surface? That was 24 miles in the air. Now imagine a sphere that large.
That’s how big UY Scuti is.
So, what would happen if UY Scuti were to swap positions with our Sun?
The Star would engulf the the entirety of Jupiter’s orbit, swallowing
the Sun, the first five planets of our solar system, and the asteroid
belt without so much as a belch. Some speculate the star may be even
larger, enough to surpass the orbit of Saturn. Not only that, but the
UY Scuti’s gravity would gobble up the larger planet and distant
planetoids of our solar system like a interstellar Pac-Man, and
whatever remained unconsumed would take thousands of years to complete
a single orbital rotation around the luminescent giant.
This video simulates what such an event would look like: