Monday, October 05, 2020

What is the Largest Area Ever Mapped?

In his short story 'On Exactitude in Science' Jorge Louis Borges famously writes about an empire which creates a map on a 1:1 scale. The map is therefore as large as the empire itself. Of course the empire's cartographers don't have to stop there. If they wanted they could create a map on 2:1 scale - this map would then be twice as big as the empire that it represents.

There is therefore no limit to the potential size of a map.

Thinking about Borges's short story this morning I got to wondering not about how big a map a could be but how large an area can be mapped. What is the largest area that has ever been mapped?

Well, in terms of interactive maps there is also no limit to the size of area that can be mapped. Let's start with our own Solar System ...

The Solar System

The Solar System is quite large. The distance from the Sun (at the center of our system) to the outer edges of the Oort Cloud (at the outer edges of our system) is around 200,000 astronomical units, which is about 3.2 light years.

OMG Space is a scaled representation of this space. Starting with the Sun, at the top of the webpage, as you scroll down OMG Space you travel out towards the edge of the Solar System, passing all the planets along the way.

The Sun and the planets and the distances between them are mapped to scale, so without using the links it will probably take you some time to scroll to the very edge of the Solar System. If the thought of scrolling across the whole Solar System sounds a little daunting you can enter hyperspace by using the planet links running across the bottom of the page. Select a planet link and the website quickly scrolls to the chosen planet.

The Milky Way

Our Solar System is just one of about 200 billion solar systems in the Milky Way. You can explore a few of those suns on ESA's Mosaic of the Milky Way.

The European Space Agency's Mosaic of the Milky Way is a huge megapixel image of the Milky Way. This huge megapixel mosaic of the central part of the Milky Way is made from thousands of individual images captured by the Vista telescope. The VISTA survey telescope is housed at ESO’s Paranal Observatory in Chile.

The Milky Way has a radius of 52,850 light years. It is about 1,000,000,000,000,000,000 km from one side to another. ESA's image however only shows one part of the Milky Way. The mosaic shows the view of that part of the Milky Way as seen from Earth, which is about 8 kpc from the center of the Milky Way on what is known as the Orion Arm.

The Milky Way isn't really that big in comparison to some galaxies. The Milky Way is around 1,000 light years in diameter. In comparison the Hercules A galaxy is 1.5 million light years across.

The Universe

The Milky Way and Hercules A are just two of the galaxies which make up the universe. The part of the universe which we can observe from Earth consists of around 200 billion galaxies. Google Sky is a very impressive interactive map of the observable universe. This is a map of a very, very big space.

The nearest neighbor to the Milky Way is the Andromeda Galaxy. The Andromeda Galaxy is approximately 2.5 million light-years from the Milky Way. It contains about one trillion start systems. The universe itself is about 93 billion light years in diameter.

We haven't yet mapped all the universe. So there is a long way to go before we have mapped the largest area possible. If we believe that the universe is finite then there is a finite amount of space to be mapped.

I started this post by stating there is no limit to the potential size of a map. This morning I started drawing a map of the universe on a 2:1 scale. When I finish I will have doubled the size of the universe.

No comments: