Earth is much closer to our galaxy’s supermassive black hole than we thought

Earth appears to have been misplaced.

According to a new map of the Milky Way, the location of the Solar System is not where we thought it was. Not only is it closer to the galactic center – and the supermassive hole in it, Sagittarius A * – it’s in orbit at a faster clip.

There is nothing to worry about; in reality we are not getting close to Sgr A *, and we do not run the risk of being swallowed. Rather, our map of the Milky Way has been adapted, more accurately identifying where we have been from the start.

And the survey beautifully demonstrates how difficult it is to map a galaxy in three dimensions from within.

It is a problem that has long devastated our understanding of space phenomena. It is relatively easy to map the two-dimensional coordinates of stars and other cosmic objects, but the distances to those objects are much more difficult to understand.

And distances are important: they help us determine the intrinsic brightness of objects. A good recent example of this is the red giant star Betelgeuse, which turned out to be closer to Earth than previous measurements suggested. This means that it is neither as big nor as bright as we thought.

Another is the CK Vulpeculae object, a star that exploded 350 years ago. It is actually much further away, which means the explosion was brighter and more energetic and requires a new explanation, as previous analyzes were performed assuming it was relatively low energy.

But we’re getting better at calculating those distances, with surveys using the best available technologies and techniques working hard to perfect our three-dimensional maps of the Milky Way, a field known as astrometry. And one of them is the VERA radio astronomy survey, conducted by the Japanese collaboration VERA.

VERA stands for VLBI (Very Long Baseline Interferometry) Exploration of Radio Astrometry and uses a number of radio telescopes across the Japanese archipelago, combining their data to effectively produce the same resolution as a telescope with a 2,300 kilometer (1,430 mile) flat of diameter. It is the same principle behind the Event Horizon Telescope that produced our very first direct image of the shadow of a black hole.

VERA, which began observing in 2000, is designed to help us calculate distances to radio-emitting stars by calculating their parallax. With its incredible resolution, watch these stars for over a year and see how their position changes relative to stars that are much further away as the Earth orbits the Sun.

(National Astronomical Observatory of Japan)

This change in position can then be used to calculate a star’s distance from Earth, but not all parallax observations are the same. VLBI can produce much higher resolution images; VERA has a breathtaking angular resolution of 10 millionths of an arc second, which should produce astrometric measurements of extraordinary accuracy.

And this is what astronomers have used to perfect the position of our Solar System in the Milky Way. Based on the first VERA Astrometry Catalog of 99 objects released earlier this year, as well as other observations, the astronomers created a map of the position and velocity of those objects.

From this map, they calculated the position of the galactic center.

In 1985, the International Astronomical Union defined the distance from the galactic center as 27,700 light years. Last year, the collaboration with GRAVITY recalculated it and found it closer, just 26,673 light-years away.

(National Astronomical Observatory of Japan)

Measurements based on VERA bring it even closer, at a distance of only 25,800 light years. And the orbital speed of the Solar System is also faster: 227 kilometers (141 miles) per second, instead of the official speed of 220 kilometers (137 miles) per second.

That change may not seem like much, but it could impact how we measure and interpret activity in the galactic center – eventually, hopefully, leading to a more accurate picture of the complex interactions around Sgr A *.

Meanwhile, the collaboration with VERA continues. Not only does it continue to make observations of objects in the Milky Way, but it joins an even larger project, the East Asian VLBI network. Together, the astronomers hope, the telescopes involved in this project could provide measurements with unprecedented accuracy.

The Vera Astrometry catalog was published in Publications of the Astronomical Society of Japan.