Where Are We in the Universe?

By: Nicole Willett

One of the most fundamental questions in science is deceptively simple: where are we? Understanding our place in the universe is not just an exercise in cosmic humility — it is essential context for appreciating why the exploration of Mars and the expansion of humanity into space matters so profoundly.

Our Cosmic Address

If we were to write our cosmic address, it would look something like this:

• Earth: A rocky planet, the third from the Sun, with a diameter of about 12,742 km.
• The Solar System: Our Sun, one ordinary star among hundreds of billions, orbits the center of the Milky Way galaxy, accompanied by eight planets, dwarf planets, asteroids, and comets.
• The Milky Way: A barred spiral galaxy containing an estimated 100-400 billion stars, spanning approximately 100,000 light-years in diameter.
• The Local Group: A collection of more than 50 galaxies, including the Milky Way and the Andromeda Galaxy, bound together by gravity.
• The Virgo Supercluster: A massive collection of galaxy clusters spanning over 100 million light-years.
• The Observable Universe: Everything we can see, containing an estimated 2 trillion galaxies, spanning 93 billion light-years in diameter.

Scale and Distance

The distances involved in astronomy are staggering. Light from the Sun takes about 8 minutes to reach Earth. Light from the nearest star, Proxima Centauri, takes over 4 years. The light we see from the most distant galaxies has been traveling for over 13 billion years.

Even within our own solar system, the distances are immense by human standards. Mars, our nearest viable destination for human exploration, is on average about 225 million km from Earth. A one-way trip takes 6-9 months with current propulsion technology.

Why This Matters for Mars Exploration

Understanding our place in the universe provides crucial context for Mars exploration:

We are isolated: Earth is the only known planet that harbors life. If something catastrophic happens to our planet, there is nowhere else to go — unless we establish a presence on another world. Mars is the most accessible and habitable alternative.

Resources are finite: Earth’s resources, while abundant, are not unlimited. Expanding to Mars and eventually beyond will give humanity access to the vast resources of the solar system.

We are explorers: Throughout human history, we have expanded into new environments, from the African savanna to the Americas to the poles. The exploration of Mars is the next logical step in this grand journey.

Perspective changes everything: Seeing Earth from space, as astronauts describe, fundamentally changes one’s perspective on our planet and our species. Establishing a presence on Mars will give humanity a new vantage point from which to understand ourselves.

The Copernican Principle

The history of astronomy is a history of discovering that we are not at the center of things. Copernicus showed that Earth orbits the Sun, not the other way around. Later astronomers showed that the Sun is not at the center of the galaxy, and the Milky Way is not at the center of the universe.

This progressive decentering has been one of science’s greatest gifts to humanity, replacing parochial geocentrism with a cosmic perspective that is both humbling and inspiring. Understanding where we are in the universe reminds us that we are part of something much larger than ourselves, and that exploring that larger universe is one of the highest expressions of human curiosity and ambition.

Mars is our next step outward. It is close enough to reach with today’s technology, rich enough in resources to support human settlement, and scientifically fascinating enough to keep generations of researchers busy. Most importantly, it represents the beginning of humanity’s journey from a single-planet species to a multiplanetary one.

When we look up at the night sky and see Mars as a bright, reddish point of light, we are looking at our future. The question of where we are in the universe has a deeply personal answer: we are at the beginning of the greatest journey our species has ever undertaken.