The universe is so vast that honestly, it’s almost impossible to really wrap the human mind around how far it reaches and how long it would take our puny selves to get from one side to the other.

If we could even manage it without expiring. Which we can’t.

Astronomers, though, need to have a grasp on things, and so they map the universe and space – but how?

These maps are important for all kinds of reasons, like keeping Earth safe and to better understand how our galaxy came to be.

And of course, there are many profound cosmological questions that still need to be answered.

Mapping the universe is made more difficult by the three-body problem, which just means that there is no exact solution for the motion of any three bodies in a gravitational field.

The universe, of course, is full of thousands of them, and physicists get around this by measuring their positions over and over again.

This is doubly important for things that impact our physical safety, like asteroids destined to come close to our orbit. Astronomers use radio, infrared, and optical telescopes to find and put them on the map, and they believe 90% of asteroids large enough to annihilate a planet have been discovered.

Recent developments in radar technology have allowed for a greater precision of the orbital parameters.

It will work to around Saturn’s orbit, but astronomers want to know more than that. So, they want to work out the distance of stars using the parallax method, which requires some trigonometry – the study of the function of angles.

Those little triangles can help work out how a star changes its position (or seems to) as the Earth moves around the Sun. From there, those same angles can help measure the distance of thousands of stars.

The Gaia spacecraft is the instrument for this job, and the European Space Agency mission has created a map of the Milky Way. It includes the position and motion of over a billion stars, exoplanets, comets, and asteroids, plus a few black holes as well.

Thanks to astronomer Henrietta Swan Leavitt , though, we can also extrapolate the position stars and planets in other universes, too. Her work shows that certain stars, called Cepheid variables, have a specific relationship between their period of variability and their intrinsic luminosity.

The luminosity of an object matters, because it tells us how far the light has traveled, allowing us to work out the distance. Astronomers now use this principle to measure extragalactic distances.

Edwin Hubble made another important discovery while studying these distant galaxies, and it’s that a majority of them are moving away from us. It was the first evidence we had that the universe is expanding.

They know this by measuring the “redshift,” a phenomenon similar to a Doppler shift, which is experienced on roads. Like, the way an ambulance siren seems to get louder as it approaches, then softer as it moves away, even though the actual pitch of the siren never changes.

The same thing happens with light if you move fast enough; things get bluer as they move toward us and redder as they shift away, and it’s caused by the expansion of the universe.

The question that remains has to do with dark matter and dark energy, which make up 95% of all matter-energy content of the universe. We’ve never actually seen it, though, and astronomers and physicists are keen to know more.

The cosmic web is shaped by all forms of matter and energy, and contains all existing galaxies. Understanding what it’s like is the subject of many upcoming surveys and studies, and scientist are hopeful major insights will result.

Human beings have been attempting to map what they know of the world, and what they believe they know about the universe, for thousands of years.

This feels like the next logical step in that ever ongoing process.

If you thought that was interesting, you might like to read about a second giant hole has opened up on the sun’s surface. Here’s what it means.