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Earth vs. Mars at a glance
| Feature | Earth | Mars |
|---|---|---|
| Mean radius | 6,371.0 km (NASA Goddard Space Flight Center/NSSDC) | 3,389.5 km (NASA Goddard Space Flight Center/NSSDC) |
| Mean diameter | About 12,742 km, calculated from NASA’s listed mean radius | 6,785 km (NASA Glenn Research Center) |
| Volume | Reference value | About 15.1% of Earth’s volume (NASA Goddard Space Flight Center/NSSDC) |
| Near-surface atmosphere | About 78% nitrogen, 21% oxygen, and 1% other gases (NASA Science) | Very thin and mostly carbon dioxide; approximate composition is 95.3% carbon dioxide, 2.7% nitrogen, and 1.6% argon (NASA/JPL InSight press kit) |
| Surface gravity | 9.82 m/s² (NASA Goddard Space Flight Center/NSSDC) | 3.73 m/s², or 0.380 of Earth’s (NASA Goddard Space Flight Center/NSSDC) |
| Water today | Abundant liquid water; global ocean covers about 71% of the surface and contains 97% of Earth’s water (NASA Science) | Water is present chiefly as ice, including in polar regions and below the surface; long-lived surface liquid water is not supported under current conditions (NASA Science) |
The measurements come from NASA pages with different publication and revision details; the sources do not establish a common measurement date for all the figures.
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How big is Mars compared with Earth?
NASA Goddard’s paired fact sheets list Earth’s mean radius as 6,371.0 km and Mars’s as 3,389.5 km. That makes Mars’s mean radius about 0.532 of Earth’s. NASA Glenn gives Mars’s mean diameter as 6,785 km, about 0.53 Earth diameters. In everyday terms, Mars is a little more than half as wide as Earth.
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Diameter is not volume. Because volume shrinks in three dimensions, Mars has about 0.151 Earth’s volume—roughly 15%, not half. NASA also notes that Mars’s surface area is nearly the same as Earth’s dry land area. That comparison helps put the planet’s scale in context, but it does not mean Mars is as large as Earth: Earth’s surface includes its oceans. See NASA’s Mars Fact Sheet and Mars overview.
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- BUILD & DISPLAY A MOVING, GLOWING SOLAR SYSTEM – With this kit, kids can customize all 8 planets and the sun, creating a stunning 3D solar system model that glows in the dark! It’s an awesome addition to any space-themed room.
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How do the atmospheres of Earth and Mars differ?
Earth’s air
Earth’s near-surface atmosphere is about 78% nitrogen and 21% oxygen, with roughly 1% other gases, according to NASA Science. This nitrogen-oxygen mixture supports the conditions familiar to people and other surface life.
Mars’s thin, carbon-dioxide-rich atmosphere
Mars has a very thin atmosphere made mostly of carbon dioxide. NASA/JPL’s InSight press-kit page gives approximate proportions of 95.3% carbon dioxide, 2.7% nitrogen, and 1.6% argon. These are approximate composition figures, not a claim that the atmosphere has the same density or pressure as Earth’s. NASA’s Earth facts, Mars facts, and JPL’s Mars at a Glance describe the respective atmospheres.
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- 【SET CONTENT】The solar system kit includes 7.87 inches of foam discs, 1 sun, 12 foam balls of different shapes, 4 foam stars, 15 bamboo sticks 15 toothpick flags, 12 Colors, 2 Brushes, 1 palette, 1 instruction. The Solar System Model Kit provides everything kids need to carry out solar system projects, kids can easily start solar system projects in school or at home!
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Does Mars have water?
Yes. Mars has water today, chiefly as ice in polar regions and beneath the surface. That is different from having stable rivers or lakes of liquid water exposed at the surface. NASA Science explains that Mars’s atmosphere is too thin for liquid water to exist for long on the surface under present conditions.
Evidence from Martian landforms and minerals points to a wetter past, when liquid water flowed across parts of the planet. NASA Glenn notes that surface features suggest past flows, but that there are no current lakes or rivers of liquid water on the surface. Earth, by contrast, has abundant surface liquid water: NASA says the global ocean covers about 71% of Earth and contains 97% of its water. Sources: NASA Mars facts, NASA Glenn’s Mars overview, and NASA Earth facts.
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- Solar system model kit: package comes with 12 pieces foam balls, 2 pieces foam rings, 15 pieces bamboo sticks, 15 pieces toothpick flags, 12 color pigments, 2 pieces painting brushes, 1 pieces paint tray palette. Now securely shipped in a sturdy cardboard box to guarantee all pieces arrive undamaged and ready for your project.
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How strong is gravity on Mars?
NASA Goddard lists mean surface gravitational acceleration as 9.82 m/s² on Earth and 3.73 m/s² on Mars. Mars’s value is 0.380 of Earth’s, commonly rounded to about 0.38 g (NASA Glenn rounds it to 0.37 g).
This is surface gravity, not a comparison of the planets’ mass or a promise about how a person would move in every situation. It describes the acceleration gravity gives an object near the surface. NASA’s paired values are in the Mars Fact Sheet; NASA Glenn provides a rounded comparison in its Mars overview.
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- CURIOUS KIDS FAVORITE TOY: Playz Electric Solar System Model Kit teaches your little astronomer the wonders of our galaxy with a 4 speed orbit motor. Ours is the biggest space toys model kit available in the USA. Perfect astronomy gift for kids!
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How cold is Mars compared with Earth?
Mars is much colder, but a single temperature number can mislead because published figures describe different measures and conditions. NASA Goddard’s fact sheets list black-body temperatures of 254.0 K for Earth and 209.8 K for Mars. Black-body temperature is a modeled comparison quantity, not the same thing as a weather-station measurement of average surface temperature.
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One free scan finds every outdated or missing driver and matches the right update for your exact hardware.Free scan · exact hardware matchFor surface conditions, NASA Science says Mars’s temperatures can reach about 20°C and fall to about −153°C. NASA/JPL’s InSight press-kit page reports a −53°C average and a range from −128°C during polar night to 27°C near the equator at midday when Mars is closest to the Sun. Those values come from different descriptions and conditions, so they should not be combined into one universal temperature range. Sources: NASA Goddard’s Mars Fact Sheet, NASA Science Mars facts, and JPL Mars at a Glance.
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- Science Kits for Kids 8-12: Complete model solar system for kids includes wood set, puzzle, and fun fact cards. This two part DIY solar system kit allows kids to build a cool model, paint, and learn about the major 9 planets. Designed for 8 & up.
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What the comparison means
Earth and Mars share a place in the same solar system, but their surface environments differ sharply. Mars is smaller in diameter and far smaller in volume; its air is thin and carbon-dioxide-rich; its gravity is under two-fifths of Earth’s; and most of its present-day water is ice rather than persistent surface liquid. The NASA/JPL Mars Quick Facts infographic, published March 23, 2020, offers a free visual comparison of core planetary facts.
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