About Dark Matter Day

What is Dark Matter Day?

On and around October 31, 2017, the world celebrated the hunt for the unseen—something that scientists refer to as dark matter. Local events organized by institutions and individuals around the planet explored its mysteries, and highlighted the experiments that could bring us closer to solving them. Since then, Dark Matter Day has become an annual celebration with labs around the world taking part. Stay tuned for information about Dark Matter Day 2021.

Less than 5 percent of the total mass and energy in the universe is the stuff we know about: like stars, planets, galaxies, and gases.

Dark matter makes up about 85 percent of the total mass of the universe, and about a quarter (26.8 percent) of the universe’s total mass and energy. Almost 70 percent (68.3 percent) of the universe’s mass and energy is composed of dark energy, another big mystery to scientists that is causing the accelerated expansion of the universe.

It’s Everywhere

All of the things that we can see in the universe only accounts for about 5% of all the matter in the universe. 95% of our universe is unknown to us. It exerts influence on what we see, but we can’t see or touch it. We call it, ‘dark matter’.


It’s Invisible
Dark matter is completely invisible to us. We have no way of seeing it because it doesn’t interact with light.
It Binds Galaxies
According to our current understanding of physics, something is holding galaxies together as they spin faster than we expected. Either there is some sort of unseen matter or force holding it together or our understanding of gravity and physics needs to be corrected. Either way, the hunt for dark matter will change how we see the universe.
It Distorts Space

When we observe distant galaxies, they appear distorted or stretched. This ‘gravitational lensing’ is caused by some unseen matter’s gravitational influence bending light around those galaxies.

Dark Matter Day is a globally recognized celebration of this cosmic riddle. It is sponsored by the Interactions Collaboration, an international community of particle physics communication specialists. Dark Matter Day was recognized around the globe on Tuesday, Oct. 31, 2017, as a day of intrigue and inquiry into the true nature of dark matter. Local events featured science experts, activities, and film presentations.

While Dark Matter Day was celebrated for the first time that year, it is not the first worldwide event to raise awareness about dark matter. In December 2010, for example, SISSA (the International School for Advanced Studies) in Trieste, Italy, organized Dark Matter Awareness Week to broadly share information about dark matter with scientists working in many different fields.

Dark Matter Day is also planned in 2021! You can sign up here to learn about upcoming Dark Matter Day 2021 events.

What Is Dark Matter?

There’s more to the universe than we can see. In fact, there’s a lot about universe that we can’t yet explain.

Dark matter, which we have so far only detected through its gravity-based effects in space, makes up about 85 percent of the total mass of the universe. So there’s a BIG part of the universe that we don’t know much about. We’re not sure if dark matter is made up of undiscovered particles, or if it can be explained by tweaking the known laws of physics. Solving the mystery of dark matter is considered one of the most pressing pursuits in particle physics and could teach us much about the history and structure of our universe.

Plan an Event

Want to plan a Dark Matter Day event in your community?

A local event could be:

  • A tour of a laboratory where dark matter research is conducted.
  • A screening of a dark matter-themed planetarium show or film.
  • An online chat or Q-and-A with a dark matter expert.
  • An in-person talk by a dark matter expert or experts.

We can help get you started!

Get Resources

This website includes resources that can help you find and connect with local dark matter experts, plan a program, and share your event with the world:

Frequently Asked Questions