Map of Mars: The Geology of the Red Planet

All the Contents of the Universe, in One Graphic

Scientists agree that the universe consists of three distinct parts: everyday visible (or measurable) matter, and two theoretical components called dark matter and dark energy.

These last two are theoretical because they have yet to be directly measured—but even without a full understanding of these mysterious pieces to the puzzle, scientists can infer that the universe’s composition can be broken down as follows:

Let’s look at each component in more detail.

Dark Energy

Dark energy is the theoretical substance that counteracts gravity and causes the rapid expansion of the universe. It is the largest part of the universe’s composition, permeating every corner of the cosmos and dictating how it behaves and how it will eventually end.

Dark Matter

Dark matter, on the other hand, has a restrictive force that works closely alongside gravity. It is a sort of “cosmic cement” responsible for holding the universe together. Despite avoiding direct measurement and remaining a mystery, scientists believe it makes up the second largest component of the universe.

Free Hydrogen and Helium

Free hydrogen and helium are elements that are free-floating in space. Despite being the lightest and most abundant elements in the universe, they make up roughly 4% of its total composition.

Stars, Neutrinos, and Heavy Elements

All other hydrogen and helium particles that are not free-floating in space exist in stars.

Stars are one of the most populous things we can see when we look up at the night sky, but they make up less than one percent—roughly 0.5%—of the cosmos.

Neutrinos are subatomic particles that are similar to electrons, but they are nearly weightless and carry no electrical charge. Although they erupt out of every nuclear reaction, they account for roughly 0.3% of the universe.

Heavy elements are all other elements aside from hydrogen and helium.

Elements form in a process called nucleosynthesis, which takes places within stars throughout their lifetimes and during their explosive deaths. Almost everything we see in our material universe is made up of these heavy elements, yet they make up the smallest portion of the universe: a measly 0.03%.

How Do We Measure the Universe?

In 2009, the European Space Agency (ESA) launched a space observatory called Planck to study the properties of the universe as a whole.

Its main task was to measure the afterglow of the explosive Big Bang that originated the universe 13.8 billion years ago. This afterglow is a special type of radiation called cosmic microwave background radiation (CMBR).

Temperature can tell scientists much about what exists in outer space. When investigating the “microwave sky”, researchers look for fluctuations (called anisotropy) in the temperature of CMBR. Instruments like Planck help reveal the extent of irregularities in CMBR’s temperature, and inform us of different components that make up the universe.

You can see below how the clarity of CMBR changes over time with multiple space missions and more sophisticated instrumentation.

What Else is Out There?

Scientists are still working to understand the properties that make up dark energy and dark matter.

NASA is currently planning a 2027 launch of the Nancy Grace Roman Space Telescope, an infrared telescope that will hopefully help us in measuring the effects of dark energy and dark matter for the first time.

As for what’s beyond the universe? Scientists aren’t sure.

There are hypotheses that there may be a larger “super universe” that contains us, or we may be a part of one “island” universe set apart from other island multiverses. Unfortunately we aren’t able to measure anything that far yet. Unravelling the mysteries of the deep cosmos, at least for now, remains a local endeavor.

Timeline: A Historical Look at Every Mission to Mars

Within our Solar System, Mars is one of the most similar planets to Earth—both have rocky landscapes, solid outer crusts, and cores made of molten rock.

Because of its similarities to Earth and proximity, humanity has been fascinated by Mars for centuries. In fact, it’s one of the most explored objects in our Solar System.

But just how many missions to Mars have we embarked on, and which of these journeys have been successful? This graphic by Jonathan Letourneau shows a timeline of every mission to Mars since 1960 using NASA’s historical data.

A Timeline of Mars Explorations

According to a historical log from NASA, there have been 48 missions to Mars over the last 60 years. Here’s a breakdown of each mission, and whether or not they were successful:

The first mission to Mars was attempted by the Soviets in 1960, with the launch of Korabl 4, also known as Mars 1960A.

As the table above shows, the voyage was unsuccessful. The spacecraft made it 120 km into the air, but its third-stage pumps didn’t generate enough momentum for it to stay in Earth’s orbit.

For the next few years, several more unsuccessful Mars missions were attempted by the USSR and then NASA. Then, in 1964, history was made when NASA launched the Mariner 4 and completed the first-ever successful trip to Mars.

The Mariner 4 didn’t actually land on the planet, but the spacecraft flew by Mars and was able to capture photos, which gave us an up-close glimpse at the planet’s rocky surface.

Then on July 20, 1976, NASA made history again when its spacecraft called Viking 1 touched down on Mars’ surface, making it the first space agency to complete a successful Mars landing. Viking 1 captured panoramic images of the planet’s terrain, and also enabled scientists to monitor the planet’s weather.

Vacation to Mars, Anyone?

To date, all Mars landings have been done without crews, but NASA is planning to send humans to Mars by the late 2030s.

And it’s not just government agencies that are planning missions to Mars—a number of private companies are getting involved, too. Elon Musk’s aerospace company SpaceX has a long-term plan to build an entire city on Mars.

Two other aerospace startups, Impulse and Relativity, also announced an unmanned joint mission to Mars in July 2022, with hopes it could be ready as soon as 2024.

As more players are added to the mix, the pressure is on to be the first company or agency to truly make it to Mars. If (or when) we reach that point, what’s next is anyone’s guess.