The disc of the Milky Way is far larger than previously thought, according to new research. Scientists now believe the galactic disc spans 200,000 light-years across.
To put this into perspective, if NASA was able to build a rocket ship that could travel at the speed of light, it would take 200,000 years for it to travel the radius of the disc.
If any brave soul got into a car and tried to drive across the Milky Way disc at 60 miles per hour, it would take him 2 trillion years to get to the other side. That is far longer than the entire time the universe has been around, which is 13.8 billion years.
How Big Is The Milky Way?
The Milky Way is a spiral galaxy characterized by a rotating flat disc where the majority of its stars are found and arms that spiral out to the sides. Beyond a certain distance from the disc, there are not too many stars.
Since astronomers began studying the Milky Way, the size of its disc has been a source of interest. Previously, scientists thought that the disc had a diameter of 100,000 light-years. In 2015, they revised this theory when a group of astronomers found galactic ripples that extended the disc's size to 150,000.
In a study published in Astronomy & Astrophysics, a team of researchers from the National Astronomical Observatories of Beijing and the Instituto Astrofisica de Canarias in Spain say new measurements have led them to conclude that the disc of the Milky Way is 200,000 light-years across.
"The disc of our Galaxy is huge," says lead author Martin Lopez-Corredoira of the IAC, "around 200 thousand light years in diameter."
Disc Stars Found On The Edge
Using data extracted from APOGEE and LAMOST, two projects that measured the velocity and chemical composition of stars, the team found a high number of stars beyond the previously set borders of the galactic disc.
Specifically, they found stars with high concentrations of heavy elements, a characteristic of stars located within the galactic disc.
The new findings also shed new light on the Sun's position within the galactic disc. It was previously thought that the sun sits at about half the radius of the disc away from the center of the galaxy. However, the new study posits that there are stars at distances three or even four times as far from the galactic center.
This means the Sun and its planetary system, including the Earth, are all closer to the center of the galaxy than previously believed.