a New image From the Hubble Space Telescope beautifully illustrates why astronomers need to be careful about distance in space.
More than a billion light-years away, two galaxies are floating in the dark, and beautiful golden snail-like snails seem to have been ignited by the collision. They are named SDSS J115331 and LEDA 2073461, and despite appearances, they don’t interact at all.
Instead, they are separated by a large distance. Their alignment is a very beautiful coincidence on their line of sight.
Galaxies in space often collide together Ultrafast dark matter to the cluster galactic nodes, where they flow toward the common galactic center.
This process is believed to be one of the methods of supermass black holes In their centers grow masses billions of times the mass of the Sun: when galaxies merge, so do their central black holes.
But space is big, and there are a lot of things in it, so scientists have to be careful when interpreting two objects that appear to be in the same place. Do they interact or overlap with a vast distance between them?
Distance is one of the most important tools we have for interpreting the universe around us. The volume, mass, and brightness of many objects cannot be measured accurately without precisely measuring the distance.
But measuring distances in space can also be difficult. You can’t tell how far something is just by looking at it unless you know how much light it’s emitting.
This is why things like Type Ia supernovae, which have a known intrinsic brightness, are a useful tool for measuring distance in space.
For objects that are relatively close, we can use parallax – the way objects move across the sky with respect to each other.
However, after a certain distance, individual objects become more difficult and harder to see. So scientists rely on Other toolslike the way the expansion of the universe extends light from distant objects.
This is how we know that SDSS J115331 and LEDA 2073461 are not in the midst of a giant collision, although there is other evidence as well: the two galaxies are very arranged; collision spoil them.
Even near the Milky Way, it can be difficult to measure distances. Recently, scientists found that the source of gamma radiation was Farther than they thought. In this case, the shape and joint alignment of the radiation and its source allowed the scientists to make the connection.
Although nested galaxies may not help scientists better understand collisions and mergers, they can be used to understand spiral galaxies.
When a farther galaxy is backlit, interstellar dust in the foreground galaxy can be easier to see. Scientists have used this twist in the alignment to map the distribution of interstellar dust in multiple galaxies.
It is unclear if the Hubble SDSS image J115331 and LEDA 2073461 will be used for this purpose. But it is incredibly beautiful.
You can download wallpaper-sized versions of this image from Hubble site.