Comparison

Sol Explorer vs Earth Primer

Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.

Head to head
About

Sol Explorer

Experience our Solar System from a first-person perspective in your own spaceship. Explore planets, moons, and space probes, traveling billions of miles across the cosmos. Learn about over 40 celestial objects and gain new perspectives on Earth and beyond.

Highlights
  • First-person spaceship exploration
  • Travel across the entire Solar System
  • Learn about 40+ celestial objects
  • Explore planets, moons, and probes
  • View from the edge of interstellar space
  • Size comparison videos
Features
Read full description

Get a first-person view of the planets and moons of our Solar System. Climb aboard your very own spaceship and explore... - It's your spaceship – fly wherever you want. - Cruise across the entire Solar System – over eight billion miles end to end. - Stop and learn about any object you see – moons, planets, and space probes. Over 40 celestial objects in all. - Observe Mars, explore the moons of Jupiter, fly through the rings of Saturn, travel to the edge of interstellar space. - Fly to the distant edge of the Solar System and look back on Earth. - Watch the Size of the Planets video and get amazing perspective on the planets in our Solar System – then explore some more.

About

Earth Primer

Explore Earth's geological processes through interactive play. Sculpt mountains, create volcanoes, and manipulate natural forces to understand planetary science in a fun, engaging way.

Highlights
  • Discover how Earth works through play
  • Control natural forces like volcanoes and tectonic plates
  • 20 different tools to unlock
  • Richly interactive geological simulations
  • Five chapters: Earth's Interior, Surface, Water Cycle, Biomes, and Sandbox
  • Sandbox mode for open-ended play
Read full description

Discover how our planet works through play! Create volcanoes, sculpt mountains, and control the forces of nature with your fingertips. Earth Primer defies existing genres, combining aspects of science books, toys, simulations, and games. It is a new kind of interactive experience which joins the guided quality of a book with open ended simulation play. • App Store Best of 2015 • Best New App • Featured Education App • "BEAUTIFUL ... ENGAGING ... WELL DESIGNED." –Kristie Lu Stout | CNN “EFFORTLESSLY BEAUTIFUL... perfectly...realizes the promise of a truly interactive textbook.” –John Brownlee | Fast Company "THE FUTURE OF EDUCATION... sets a high benchmark for what educational apps should be aspiring to." –Luke Dormehl | Cult of Mac “INSPIRING ... a reminder that interactive media is a young and undeveloped world itself.” –Kyle VanHemert | WIRED “PLAYFUL, child-like, beautifully designed reenvisioning of the book” –IndieCade “The MOST AWESOME APP EVER for teaching Geomorphology to a young audience” –Alan Parkinson | Award Winning Teacher “one of the most deluxe, and memorable educational apps available... AN ABSOLUTE MUST” 5/5 –Trevor Sheridan | Apple n Apps “A TOUR DE FORCE” –Bret Victor "This is much more than a toy. It is a catalyst for thinking about our world. ... TRULY A JOY." –Samuel Arbesman | WIRED "I want every book to be this awesome. ...ABSOLUTELY WORTH EVERY CENT." –Owen Williams | The Next Web Features • Discover how Earth works through play. • The forces of nature are at your fingertips—make volcanoes, shape sand dunes, form glaciers, sculpt mountains, push around tectonic plates, paint with wind, heat up magma—and more! • 20 different tools to unlock. • Richly interactive geological simulations. • Five chapters: Earth's Interior, Surface, Water Cycle, Biomes, and Sandbox. • Sandbox mode.

Screenshots

Sol Explorer4 screens

Verdict

The call

The clearest difference is price: Sol Explorer at Free against Earth Primer's $9.99. Sol Explorer also leads on review sentiment (100% vs 75%) and rating (5.0 vs 4.7). Earth Primer's advantage is update cadence (every 3 weeks vs every 86 months) and ratings volume (35 vs 6). On ads, in-app purchases and device support there is nothing between them.

Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS

CostPrice · In-app purchases · Ads · Monetization

Sol Explorer is free to download; Earth Primer costs $9.99 up front. Neither carries in-app purchases, so what you see is what you pay.

ReceptionRating · Positive reviews · Number of ratings

Sol Explorer holds the better App Store score, 5.0 against 4.7. That said, the two scores are not equally well evidenced: Earth Primer has 35 ratings behind it against 6, so its average is the more settled of the two. Written reviews point the same way: 100% of Sol Explorer's written reviews are positive against 75% of Earth Primer's.

UpkeepUpdate frequency

Sol Explorer ships an update every 86 months, Earth Primer every 3 weeks. Both last shipped on November 6, 2026.

Scorecard7 real differences · 3 level
Sol Explorer versus Earth Primer: the parameters behind the verdict, then further details
ParameterSol ExplorerEarth Primer
PriceFree — better$9.99
Rating5.0 (6 ratings) — better4.7 (35 ratings)
Positive reviews100.0% of reviews — better75.4% of reviews
Number of ratings635 — better
Update frequencyEvery 86 monthsEvery 3 weeks — better
AdsNoNo
In-app purchasesNoNo
MonetizationFree — betterPaid
DevicesiPhone, iPad — betteriPad
Requires iOS16.07.0 — better
Further details — not scored
Size268 MB185 MB
Age rating4+4+
DeveloperReason InteractiveChaim Gingold

Customer experience

Sol Explorer

All ratings6 ratings
Positive100.0%
Neutral0.0%
Negative0.0%
Written reviews5 reviews
Positive100.0%
Neutral0.0%
Negative0.0%

Earth Primer

All ratings35 ratings
Positive91.4%
Neutral2.9%
Negative5.7%
Written reviews65 reviews
Positive75.4%
Neutral3.1%
Negative21.5%

Bugs and requests

Sol Explorer

Not enough reviews yet to summarise bugs or requests.

Earth Primer

Reported bugs

11 issues
  • 🐛 Grayed out options in sandbox mode on iOS 12.1.3
  • 🐛 Unreadable on iPad Pro
  • 🐛 Broken software on iPad Pro
  • 🐛 Still not working on iPad Pro
  • 🐛 Does not work on iPad Pro
Show 6 more
  • 🐛 Stuck in table of contents on iPad Pro
  • 🐛 Does not render correctly on iPad Pro
  • 🐛 App not working well on new iPad Pro
  • 🐛 App gets stuck on loading screen
  • 🐛 Cannot get past the second slide, no directions
  • 🐛 Never able to get beyond the "surface" screen

Requested features

15 requests
  • Add a sandbox version for 2D earth
  • Add 3D models for volcanoes
  • Include simulated volcanic eruptions, earthquakes, and tsunamis
  • Add a sandbox simulation program for these phenomena
  • Add humans and animals to sandbox mode to observe civilization building and impact
Show 10 more
  • Allow adjustment of time passing rate and pausing time
  • Increase surface area in sandbox mode for larger landscapes
  • Add more features and content
  • Add humans, animals, apes, tsunamis, waterfalls
  • Add aliens or dinosaurs
  • Add hurricanes and twisters to sandbox mode
  • Add a time speed option
  • Add volcanoes and magma to sandbox mode
  • Add a pollution feature
  • Add meta-material about algorithms and models for professional teaching

In-app purchases

None

Sol Explorer

No in-app purchases

None

Earth Primer

No in-app purchases

Questions

Is Sol Explorer free?
Sol Explorer is free to download, with no in-app purchases.
Is Earth Primer free?
Earth Primer costs $9.99, with no in-app purchases.
Which has better reviews, Sol Explorer or Earth Primer?
Sol Explorer is rated higher. Sol Explorer averages 5.0 out of 5 from 6 ratings, while Earth Primer averages 4.7 from 35 ratings.
Do Sol Explorer or Earth Primer have ads?
Neither Sol Explorer nor Earth Primer shows ads.
Which is updated more often, Sol Explorer or Earth Primer?
Sol Explorer ships an update every 86 months, and Earth Primer every 3 weeks. Most recently, Sol Explorer was updated on November 6, 2026 and Earth Primer on November 6, 2026.

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