What kind of planet is earth and mars

Scientists think the Valles Marineris formed mostly by rifting of the crust as it got stretched. Individual canyons within the system are as much as 60 miles km wide. The canyons merge in the central part of the Valles Marineris in a region as much as miles km wide. Large channels emerging from the ends of some canyons and layered sediments within suggest that the canyons might once have been filled with liquid water.

Mars also has the largest volcanoes in the solar system, Olympus Mons being one of them. The massive volcano, which is about miles km in diameter, is wide enough to cover the state of New Mexico. Olympus Mons is a shield volcano, with slopes that rise gradually like those of Hawaiian volcanoes, and was created by eruptions of lava that flowed for long distances before solidifying.

Mars also has many other kinds of volcanic landforms, from small, steep-sided cones to enormous plains coated in hardened lava. Some minor eruptions might still occur on the planet today. Channels, valleys and gullies are found all over Mars, and suggest that liquid water might have flowed across the planet's surface in recent times. Some channels can be 60 miles km wide and 1, miles 2, km long. Water may still lie in cracks and pores in underground rock.

A study by scientists in suggested that salty water below the Martian surface could hold a considerable amount of oxygen, which could support microbial life. However, the amount of oxygen depends on temperature and pressure; temperature changes on Mars from time to time as the tilt of its rotation axis shifts. Many regions of Mars are flat, low-lying plains.

The lowest of the northern plains are among the flattest, smoothest places in the solar system, potentially created by water that once flowed across the Martian surface. The northern hemisphere mostly lies at a lower elevation than the southern hemisphere, suggesting the crust may be thinner in the north than in the south. This difference between the north and south might be due to a very large impact shortly after the birth of Mars. The number of craters on Mars varies dramatically from place to place, depending on how old the surface is.

Much of the surface of the southern hemisphere is extremely old, and so has many craters — including the planet's largest, 1,mile-wide 2, km Hellas Planitia — while that of northern hemisphere is younger and so has fewer craters. Some volcanoes also have just a few craters, which suggests they erupted recently, with the resulting lava covering up any old craters. Some craters have unusual-looking deposits of debris around them resembling solidified mudflows, potentially indicating that the impactor hit underground water or ice.

In , the European Space Agency's Mars Express spacecraft detected what could be a slurry of water and grains underneath icy Planum Australe. Some reports describe it as a "lake," but it's unclear how much regolith is inside the water. This body of water is said to be about Its underground location is reminiscent of similar underground lakes in Antarctica, which have been found to host microbes.

Vast deposits of what appear to be finely layered stacks of water ice and dust extend from the poles to latitudes of about 80 degrees in both Martian hemispheres. These were probably deposited by the atmosphere over long spans of time. On top of much of these layered deposits in both hemispheres are caps of water ice that remain frozen year-round.

Additional seasonal caps of frost appear in the wintertime. These are made of solid carbon dioxide, also known as "dry ice," which has condensed from carbon dioxide gas in the atmosphere. In the deepest part of the winter, this frost can extend from the poles to latitudes as low as 45 degrees, or halfway to the equator.

The dry ice layer appears to have a fluffy texture, like freshly fallen snow, according to a report in the Journal of Geophysical Research-Planets.

Mars is much colder than Earth, in large part due to its greater distance from the sun. The average temperature is about minus 80 degrees Fahrenheit minus 60 degrees Celsius , although it can vary from minus F minus C near the poles during the winter to as much as 70 F 20 C at midday near the equator. The carbon-dioxide-rich atmosphere of Mars is also about times less dense than Earth's on average, but it is nevertheless thick enough to support weather, clouds and winds. The density of the atmosphere varies seasonally, as winter forces carbon dioxide to freeze out of the Martian air.

In the ancient past, the atmosphere was likely significantly thicker and able to support water flowing on the planet's surface.

Over time, lighter molecules in the Martian atmosphere escaped under pressure from the solar wind, which affected the atmosphere because Mars does not have a global magnetic field. NASA's Mars Reconnaissance Orbiter found the first definitive detections of carbon-dioxide snow clouds , making Mars the only body in the solar system known to host such unusual winter weather. Many of the same physical land features we see on Earth also exist on Mars. But the sheer size of some landforms on Mars dwarfs that of similar features on Earth.

The table below compares many of Mars' conditions, specifications and features with those on Earth. Atmosphere composition. Carbon dioxide Atmosphere pressure. Valles Marineris 7 km 4. Jupiter and Saturn are sometimes called the gas giants, whereas the more distant Uranus and Neptune have been nicknamed the ice giants. This is because Uranus and Neptune have more atmospheric water and other ice-forming molecules, such as methane, hydrogen sulfide and phosphene, that crystallize into clouds in the planets' frigid conditions, according to the Planetary Society.

For perspective, methane crystallizes at minus Fahrenheit minus degrees Celsius , according to the U. National Library of Medicine. The IAU defines a true planet as a body that circles the sun without being some other object's satellite; is large enough to be rounded by its own gravity but not so big that it begins to undergo nuclear fusion, like a star ; and has "cleared its neighborhood" of most other orbiting bodies. Yeah, it's a mouthful. But that restrictive definition helped isolate what should and should not be considered a planet — a problem that arose as astronomers discovered more and more planet-like objects in the solar system.

Pluto was among the bodies that didn't make the cut and was re-classified as a dwarf planet. The problem with Pluto, aside from its small size and offbeat orbit, is that it doesn't clear its neighborhood of debris — it shares its space with lots of other objects in the Kuiper Belt. Still, the demotion of Pluto remains controversial.

The IAU planet definition also put other small, round worlds into the dwarf planet category, including the Kuiper Belt objects Eris , Haumea and Makemake.

Ceres , a round object in the Asteroid Belt between Mars and Jupiter, also got the boot. Ceres was considered a planet when it was discovered in , but it was later deemed to be an asteroid.

That still didn't quite fit because it was so much larger and rounder than the other asteroids. Astronomers instead deemed it a dwarf planet in , although some astronomers like to consider Ceres as a 10th planet not to be confused with Nibiru or Planet X.

Below is a brief overview of the eight true planets in our solar system , moving from that closest to the sun to farthest from the sun:. Zipping around the sun in only 88 days, Mercury is the closest planet to the sun, and it's also the smallest, only a little bit larger than Earth's moon.

Because its so close to the sun about two-fifths the distance between Earth and the sun , Mercury experiences dramatic changes in its day and night temperatures: Day temperatures can reach a scorching F C , which is hot enough to melt lead.

Meanwhile on the night side, temperatures drop to minus F minus C. Mercury has a very thin atmosphere of oxygen, sodium, hydrogen, helium and potassium and can't break-up incoming meteors, so its surface is pockmarked with craters, just like the moon. Among those findings was the discovery of water ice and frozen organic compounds at Mercury's north pole and that volcanism played a major role in shaping the planet's surface. The second planet from the sun, Venus is Earth's twin in size.

Radar images beneath its atmosphere reveal that its surface has various mountains and volcanoes. But beyond that, the two planets couldn't be more different. Because of its thick, toxic atmosphere that's made of sulfuric acid clouds, Venus is an extreme example of the greenhouse effect.

It's scorching-hot, even hotter than Mercury. There are more planets than stars in our galaxy. The current count orbiting our star : eight. The inner, rocky planets are Mercury , Venus , Earth , and Mars. The outer planets are gas giants Jupiter and Saturn and ice giants Uranus and Neptune. Beyond Neptune, a newer class of smaller worlds called dwarf planets reign, including longtime favorite Pluto.

Thousands more planets have been discovered beyond our solar system. Scientists call them exoplanets exo means "from outside".

The key difference between a planet and a dwarf planet is the kinds of objects that share its orbit around the Sun. Pluto, for example, has not cleared its orbit of similar objects while Earth or Jupiter have no similarly-sized worlds on the same path around the Sun. Like planets, dwarf planets are generally round Haumea looks like an overinflated football and orbit the Sun.