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1Clear out junk files and repair common Windows errors2Scan for outdated or missing drivers - takes under a minute3Repair Windows errors before they cause bigger problemsEarth and Mars formed from rocky material in the young Solar System, but they followed different paths as they grew and evolved. Mars is much smaller, has no global magnetic field today, lacks Earth’s plate-tectonic recycling, and holds much of its ancient water in crustal minerals—while some water escaped to space. Those differences help explain why Mars, once home to rivers and lakes, is now cold and dry at the surface.
How did Earth and Mars form?
About 4.5 billion years ago, dust and rocky grains orbiting the young Sun clumped under gravity. As they collided and accumulated, they formed larger bodies, including planetary embryos. Continued growth and heating separated dense material toward the center and lighter rock above it, producing the familiar layers of core, mantle, and crust. NASA describes Mars as having all three layers, as does Earth. NASA Science’s Mars facts gives this broad formation picture.
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The two planets share that basic origin, but their exact growth histories need not have been identical. Martian meteorites provide rare samples of Mars’s interior and crust. A NASA account of a 2013 study described two meteorites with different water signatures: one reflected water associated with the deep interior, while another included crustal material that had interacted with the atmosphere. The more water-rich sample contained ten times as much water as the low-water sample. The analysis also pointed to planetary building blocks for Mars’s interior water similar to those that formed Earth. NASA Johnson Space Center’s meteorite report explains the comparison.
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Fix the driver behind crashes, sound loss and screen glitchesFind Drivers →Repair Windows errors before they cause bigger problemsFix Now →Mars may have assembled earlier than Earth, but that chronology is an inference, not a settled sequence. NASA Astrobiology’s 2026 summary of shergottite research says Mars may have accreted before Earth. It also describes continued supply of material during the Solar System’s first 50–100 million years as a factor in the broadly similar abundances of highly siderophile elements in the two planets. NASA Astrobiology’s account of Mars’s accretion presents the evidence and its limits.
#1 Best Overall
- 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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Why is Mars smaller than Earth?
Both planets grew by accumulating material, but they did not end up with the same mass. NASA lists Mars’s radius as 3,390 kilometers and describes it as about half Earth’s size. That difference matters because a smaller planet has a different interior and a different capacity to retain heat and atmosphere over time. It is useful context for Mars’s later history, but size alone does not explain every difference between the planets.
What evidence shows that Mars once had water?
Ancient valleys, deltas, lakebeds, and flood features on Mars indicate that liquid water once flowed and pooled at the surface. NASA points to evidence for enormous floods about 3.5 billion years ago. This landform evidence establishes a wetter past; it does not, by itself, specify the planet’s complete water inventory or how much water remains in each reservoir.
Rank #2
- 【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!
- 【Space Enlightenment】The Solar System Model Kit allows kids to color and build their own solar system model, providing kids a more intuitive understanding of the planet in the solar system. With a Solar System Instruction, which introduces kids to the relevant details of the solar system, sparking their curiosity and desire to explore astronomy and science!
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A NASA/JPL summary of research published in 2021 reconstructed enough early Martian water to cover the planet in a global ocean roughly 100–1,500 meters deep—about half the volume of Earth’s Atlantic Ocean. That is a study-based reconstruction, not a directly observed ancient ocean depth. NASA/JPL’s 2021 account describes the estimate and the evidence behind it.
Where did Mars’s water go?
It did not all escape into space. Some water was lost from the atmosphere, but water also reacted with rock and became locked in clays and other hydrated minerals in the crust. The NASA/JPL summary of the 2021 study reports an estimate that 30–99% of Mars’s water may be trapped in crustal minerals. That wide range is a research estimate, not a direct census of every reservoir. The study’s lead author, Eva Scheller, told NASA, “Atmospheric escape doesn’t fully explain the data that we have for how much water actually once existed on Mars.”
Rank #3
- 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.
- Variety of Sizes for Visual Learning: The kit includes 10 differently sized foam balls (as pictured) to visually represent the relative scale and hierarchy of the Sun, planets, and Pluto. This hands-on approach helps learners easily observe and understand planetary size relationships.
- Upgraded Premium Paint Set: Features our enhanced paint set with 12 vibrant colors (increased from 8), each in a larger 5ml pot for richer coverage, longer use, and more creative possibilities.
- Easy to assemble: You can identify the different planets by writing the planet's name on a blank toothpick flag and inserting it into a foam ball. No glue required, they can be easily assembled using bamboo skewers, create your planetary model to understand how our solar system is arranged.
- Fun learning tool: You and your kids had a great time painting and putting this together and learnt a lot about the planets in the process. It was a decent lesson representing the Solar system for a young child. Perfect for handmade craft, DIY decoration, school project, science projects and more.
Earth and Mars also differ in how they process water-bearing rock. Earth’s plate tectonics carries old crust into the mantle, where material is processed and water and other compounds can return through volcanism. Mars has no tectonic plates, so hydrated crust can remain stored rather than undergoing the same global recycling cycle.
How minerals can hold water for a long time
A 2017 study by Jon Wade and coauthors proposed a mechanism for persistent storage in Mars’s crust: in a stagnant-lid regime, mafic crust can be buried, and its minerals can retain water at depth. The authors’ calculations found that metamorphic mineral assemblages in Martian lavas could hold about 25% more structurally bound water than metamorphosed terrestrial basalts. They also estimated that hydrous minerals could occupy more than 9% by volume of the Martian mantle, compared with about 4% of Earth’s mantle. These are modeled comparisons of mineral capacity, not measurements of the total water inventories of the two planets. Wade et al.’s 2017 Nature paper sets out the analysis.
Rank #4
- 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!
- HANDS ON PROJECT: 75+ premium parts combined with a color instruction manual makes for an intuitive DIY assembly. Loaded with fun educational facts about physics, astronomy, science, and engineering. Large model measures 26" x 18" x 11"
- OUTER SPACE CREATIVITY: Children can paint their own planets with the included paint set and foam balls or use the high quality laser painted planets for an excellent science fair or school project display!
- STUNNING VIEWS: The sun is a portable HD projector that projects 8 beautiful planets on any surface! Many kids use it as a cool nightlight or flashlight. (4x AA BATTERIES NOT INCLUDED)
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How did Mars’s magnetic field and atmosphere change?
Mars has no global magnetic field today, although strongly magnetized parts of its southern crust preserve traces of a field from about 4 billion years ago. Its present atmosphere is thin and consists mostly of carbon dioxide, nitrogen, and argon, according to NASA’s planetary reference page.
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Random freezes, missing sound and display glitches usually trace back to one bad driver. Find and replace yours safely.Free scan · under a minuteThe history of the magnetic field and atmosphere is relevant to Mars’s climate and water loss, but it is not a complete explanation on its own. The available evidence points to more than one fate for water: some escaped to space, while some became incorporated into crustal minerals. Earth’s continuing tectonic recycling provides another contrast, helping move water-bearing material between surface and interior.
Best Value
- 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.
- Science Fairs & More: Bring the planets to life with our Nine Planets kit. Makes the perfect realistic solar system model for elementary school science fairs & more. Proudly display in a bedroom, science fair, or classroom. For girls and & boys.
- Planetary Enlightenment: Foster a love for learning with our solar system project, an engaging educational science kit that makes complex concepts easy to understand and enjoyable for young minds. Includes fact cards for quick and accurate solar system information.
- Planetary Delight: Unleash creativity and curiosity with our solar system project kit . Children will delight in their exploration of the universe while having fun accomplishing this all in one kit. We offer the perfect science kits for kids age 8-12.
- Craft & Learn: Everything you need to build the wood model, paint the major planets, and build the puzzle. Includes The Sun, Mercury, Earth, Jupiter, Uranus, Venus, Mars, Saturn, and Neptune. Includes paint and brushes. Build the model in approximately 1-2 hours.
Earth and Mars compared
| Feature | Earth | Mars |
|---|---|---|
| Broad origin | Assembled from material in the early Solar System. | Assembled from material in the early Solar System; Mars’s interior-water building blocks appear similar to Earth’s. |
| Size | Larger than Mars; a comparable radius is not stated in the cited NASA Mars reference. | Radius: 3,390 km; NASA describes Mars as about half Earth’s size. |
| Accretion timing | Exact comparative timing is not established here. | May have accreted before Earth; NASA Astrobiology, 2026, presents this as a possibility. |
| Global magnetic field today | Not stated in the cited sources. | No global magnetic field today; southern crustal traces record an ancient field. |
| Water and crust recycling | Plate tectonics recycles old crust through the mantle; volcanism returns water and other compounds. | No tectonic plates; hydrated crust can remain stored, while some water also escaped to space. |
Why did two related planets become so different?
The contrast is not a tale of one planet keeping all its water and the other losing all of it. Earth and Mars began with broadly related raw materials, then diverged through differences in size, interior evolution, magnetic and atmospheric history, and the movement—or lack of movement—of water-bearing crust. Mars’s ancient surface records rivers, lakes, and floods; its present-day dryness coexists with water stored in minerals and water lost to space. Earth’s plate tectonics, by contrast, continually recycles crust and helps return water through the planet’s interior and volcanism.
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