Solar wind may have contributed to Mars losing its atmosphere

Martian skies and sunsets resembled Earth's hundreds of millions of years ago

Evidence suggests that Mars has had a thicker atmosphere, which included greenhouse gases, and a magnetic field in its past, resembling Earth's current composition. After losing its magnetic field—the protection from solar wind—the atmosphere and its associated atmospheric phenomena gradually disappeared.

Mars once had oceans and a thick atmosphere

It formed over millions of years as small clumps of matter orbiting the sun smashed together, solidified, and cooled. Geological features indicate the presence of past surface water, which evaporated away due to the planet's weak gravitational field.

Did Mars ever look like Earth?

Mars formed at the same time as the rest of the solar system, about 4.6 billion years ago. Today, Mars is a cold, dry world with a thin atmosphere. However, there is evidence that Mars was once much more habitable, covered in flowing rivers a large bodies of water. Scientists believe over time the planet lost its magnetic field, leading to the loss of atmosphere and ultimately the evaporation of water.

Dust particles on Mars can generate lightning

Through triboelectric charging, sand and dust on the Martian surface can become electrified when they rub against one another, causing friction to displace electrons and create charged particles. If this matter forms a strong enough electric field, it can overcome atmospheric insulation and produce electrical discharges, resembling lightning on Earth.

Geological features on Mars' surface provide evidence of massive past flooding

The presence of river valleys, enormous canyons, and other structures carved by water on Earth suggests that water flowed abundantly across Mars' surface. The layering of rocks in the walls of these structures indicates the intensity and volume of these flows.

Ambient sounds on Mars are lower-pitched and more muted than those on Earth

The planet's thin atmosphere absorbs higher frequencies, and audio captured by the Perseverance rover from the Ingenuity Mars helicopter revealed that sound waves travel farther than previous atmospheric models suggested.

Hypotheses on the origins of Earth's water, from comets and asteroids to magma oceans

Before Earth's atmosphere formed, any liquid water would have boiled off, preventing the accumulation of water early on to create today's oceans. Planetary scientists continue to debate whether this water was delivered later from comet or asteroid collisions or via reactions between iron oxide in Earth's molten surface and hydrogen gas from the planetary nebula.

Some 19th century astronomers thought Mars was inhabited

As telescope technology advanced, astronomers became able to observe the surfaces of objects in our solar system with greater detail. The dips, valleys, and lines crisscrossing Mars, particularly, captured onlookers' imagination, leading some to speculate that the seemingly organized features could only have been created by an intelligent civilization.

Why Earth's atmosphere constantly loses the universe's lightest elements to space

The masses of hydrogen and helium are too small for these gases to be held by Earth's gravitational force, particularly when these atoms are given energy from collisions with high-speed particles from the sun. Although the planet loses a meter-wide balloon's worth of hydrogen every second, it will still take billions of years to exhaust the planet of this element.

Except for Mercury, every planet in the solar system experiences auroras

Lacking magnetic fields, Venus and Mars exhibit auroras when the solar wind collides directly with their atmospheres, without deflection. Some particles behind the atmospheric collisions that generate auroras on gas giants come from their moons and the surrounding environments.

Asteroids are artifacts of water's presence in the solar system

Asteroids contributed to planet formation and carried water from the solar system's outer reaches toward the center. They were also early providers of the necessary elements and conditions for life to evolve on Earth.

The inhabitability of the Martian environment presents significant colonization risks

Terraforming the thin atmosphere, toxic dust, extreme cold, and lack of magnetic field is infeasible, given limitations to the size of what can be sent to Mars. NASA and SpaceX are instead exploring creating underground shelters.

Mars' orbit may provide evidence that dark matter is made of primordial black holes

Physicists at MIT have found that, statistically, one such microscopic black hole should pass through the solar system every decade, which they predict would introduce a detectable wobble in Mars' orbit. Such black holes would have formed in the early universe from collapsing gas clouds and scattered as the universe expanded.

Besides Earth, Mars is the only possibly habitable planet in our solar system

Sending humans to Mars in the following decades poses significant challenges, from the vast distance covered to get materials there to powering technology during weekslong dust storms. Research is ongoing to develop life support systems that can regenerate or recycle consumables.

The sun emits a continuous stream of plasma known as the solar wind

Composed of charged particles—electrons and ions—the solar wind is deflected around the Earth by the planet's magnetic field. More powerful solar storms, known as coronal mass ejections, are short-lived but produce huge clouds of plasma that disrupt technology upon reaching Earth.

Particles found in Martian air pose significant risks to human lungs

Ultrafine dust, just 3 micrometers wide, is small enough to bypass lung defenses and enter the bloodstream, where its highly reactive chemicals can cause thyroid disease. Silica in the dust can also cause silicosis, a chronic and incurable lung disease.

Perseverance captures an aurora on Mars

The Perseverance rover captured the first visible Martian aurora, offering insights into Mars's atmospheric interactions. A coronal mass ejection likely triggered the aurora since the planet lacks a global magnetic field.

Inhabiting Mars without terraforming might be accomplished with 'worldhouses'

A network of interconnected, airtight bubbles would require several orders of magnitude fewer materials than those required to re-establish the entire planet's atmosphere to resemble Earth. However, the whole network would be compromised by a single micrometeor impact that destroys the air seal.

If the sun disappeared, we would not know about it for 8 minutes and 20 seconds, at which point the Earth would suddenly move in a straight line on its way out of the solar system.

Space weather phenomena, including solar flares, coronal mass ejections, and solar wind, are driven by the sun's magnetic field and can affect Earth's ground- and space-based technological systems.

From the surface, Mars can appear butterscotch, golden brown, and even green

Images from orbiters, landers, and rovers show that Mars has a mix of surface colors resulting from variations in the mineral compositions of different regions. The reddish tint when viewed from Earth comes from kicked up particles of rusted iron.

Mars features distinct geographic contrasts between its northern and southern regions

Unlike the uniform terrains found in most rocky planets, Mars has a smooth, low northern hemisphere and a rough, high southern hemisphere with much thicker crust. This dichotomy may originate from a massive collision early in the planet’s history.

Understanding why charged particles from the sun protect Earth from more dangerous particles

The solar wind engulfs the solar system in a protective bubble called the heliosphere, which was first theorized in the late 1950s based on studies of cosmic rays—high-energy particles traveling through space at near light speed. The heliosphere shields the solar system from much of this ionizing radiation originating elsewhere in the Milky Way.

How the loss of Earth's atmosphere would cause oceans to boil at freezing temperatures

Many phenomena requiring air pressure, from the flight of birds and aircraft to the act of breathing, would no longer be possible. Because sound travels through vibrating air molecules, the loss of the planet's atmosphere would also create a silent environment. Even during daytime hours, the sky would resemble a clear night sky.

According to the Grand Tack model, Saturn stopped Jupiter's inward migration

The model suggests Jupiter migrated inward early in its formation and cleared debris from the inner orbits of terrestrial planets. Saturn's gravitational pull saved what was left of the inner solar system to form Mercury, Venus, Earth, and Mars.

Tidally locked exoplanets experience extreme atmospheric temperatures

On worlds like WASP 76b, which orbits its host star approximately 3% the Earth-sun distance, temperatures on its day side can vaporize iron. Winds more than 14 times the speed of sound blow this material to its night side, where it condenses and falls as liquid metal.

NASA's ESCAPADE mission will study Mars' atmosphere

The $80M mission—a collaboration between private companies, universities, and NASA—sent two copy machine-sized orbiters on a Blue Origin rocket to the red planet to study its magnetic field and atmospheric loss.

Why Earth will be made uninhabitable by the sun far sooner than when the sun dies

The star has enough fuel to continue fusing hydrogen into helium for another 5 billion years, but the gradual increase in core temperature from these reactions will brighten the sun by 10% every billion years. Some models predict that the increased radiation will be enough to vaporize all of Earth's surface water about 1 billion years from now, long before the sun becomes a red giant and disintegrates the planet.

The Mars Climate Orbiter—a $125M spacecraft designed to study Martian weather and climate—was lost because ground software used imperial units while onboard software used metric units.

Jupiter’s size forced the creation of modified planetary formation models

Since solar winds remove gases from protoplanetary disks within millions of years of a star’s birth, models needed to provide a mechanism to jump-start Jupiter’s formation and growth. The solution involved incorporating pebbles of matter into the disk.

Early Earth lifeforms likely made energy via mineral reactions, not sunlight

Earth's initial atmosphere was filled with carbon dioxide, methane, and water, with most oxygen locked away in the rocky crust. Over time, bacteria evolved to slowly release that oxygen into the atmosphere by breaking down rock.

Explore a world map of Mars

The yellows spots scattered across the map indicate meteor impacts while the red regions represent volcanoes and their associated lava flows. The varying shades of brown indicate cratered highlands and midlands, which make up most of the southern hemisphere.

A four-billion-year-old meteorite reignited the debate about life on Mars

Recovered from Antarctica in 1984, ALH84001 contained organic compounds, magnetite and iron sulfide grains of potential biological origin, and features that resembled fossilized bacteria. With technological advancements, scientists found abiotic origins for these features in the following decades.

Because it loses more atmospheric gas to outer space than the cosmic dust it collects as it moves through space, the Earth loses about 50,000 metric tons of mass every year.

Everything you need to know about Mars

The Lunar and Planetary Institute provides assorted resources about the red planet, Mars. Review this basic 101 level introduction and get to know our solar system neighbor. Learn about Mars' planet-wide dust storms, staggeringly high mountains (six of which dwarf Mount Everest), and whether there's water there below the surface.

The sun will become a red giant after it exhausts the hydrogen fuel in its core, causing gravity to collapse the core and heat it enough for the surrounding hydrogen shell to ignite, releasing enough energy to cause the star to swell.

Our solar system is currently traveling through a 'dark matter hurricane'

The phenomenon refers to a stream of cosmic debris, including stars and dark matter, leftover from a small galaxy that passed too close to the Milky Way and was torn apart. There are over 30 such streams known in our galaxy, and the stream intersecting the solar system is predicted to continue to do so for millions of years.

Fly through the Valles Marineris, the largest canyon in the solar system

Stretching farther than the width of the continental US and with depths as much as four times those of the Grand Canyon, the Valles Marineris is believed to have formed when Mars’s crust tore open during intense volcanism in the planet’s past.

The Viking landers were the first spacecraft to conduct experiments on Mars

NASA’s Viking 1 and 2 missions tested soils for signs of life, captured images, and studied the Martian atmosphere, revealing evidence of ancient water flow, volcanic soil, and a thin carbon dioxide atmosphere.