Best Space Encyclopedia for Kids (2026): 5 Picks Compared

Finding the best space encyclopedia for kids starts with matching the book’s visual detail and reading level to your young astronomer’s curiosity. Whether you are shopping for a preschooler asking about the moon or an older elementary student researching galaxies, a quality reference book makes complex astronomy approachable. We compared space encyclopedias by listed reading age, grade level, print length, and publisher details to help you choose the right volume.

ShelfAnswers earns a commission when you buy through links on this page, at no extra cost to you. As an Amazon Associate I earn from qualifying purchases. Affiliate disclosure.

The picks

#	Product	Shelf Score	Buy
1	Space Encyclopedia by Aguilar	9.8/10	Buy
2	Knowledge Encyclopedia Space by DK	9.8/10	Buy
3	Mysteries of the Universe by Gater	9.7/10	Buy
4	Space Box Set by Wonder House Books	9.6/10	Buy
5	Little Kids Space by Hughes	9.5/10	Buy

1

Space Encyclopedia by Aguilar

National Geographic Kids·9.8/10 Shelf Score

i

The Shelf Score runs from 9.2 to 9.8 and weighs fit for the reader or goal (35 points), contents and edition (25), value (25) and listed reading age or level (10, where the listing gives one), using only what the book listing states. How we pick ›

An illustrated reference covering the solar system, dwarf planets, and space exploration with NASA photography.

Check price on Amazon

Pros

• Updated second edition includes recent NASA photography and coverage of dwarf planets
• Grade level 3 to 7 matches middle grade readers looking for school report material
• Authored by astronomer David A. Aguilar with 208 illustrated pages
• Reading age of 6 to 10 years covers early elementary through fifth grade

Cons

• Reading age is marked as from customers rather than stated by the publisher
• Broad scope means individual topics receive only a few pages of overview
• At 208 pages, the heavy volume is better suited for a desk than travel
• Grade level and customer reading age bands have slightly different starting points

2

Knowledge Encyclopedia Space by DK

DK·9.8/10 Shelf Score

i

The Shelf Score runs from 9.2 to 9.8 and weighs fit for the reader or goal (35 points), contents and edition (25), value (25) and listed reading age or level (10, where the listing gives one), using only what the book listing states. How we pick ›

A visual guide using 3D computer-generated imagery to explore galaxies, stars, and the International Space Station.

Check price on Amazon

Pros

• Uses 3D computer-generated imagery and cutaway diagrams to show spacecraft and celestial bodies
• Print length of 208 pages revised and updated for 2020 with engineering discoveries
• Grade level 4 to 7 provides detailed scientific explanations for older kids
• Published on January 18, 2022 as a new edition in DK's Knowledge series

Cons

• Listing gives grade level 4 to 7 while customer reading age starts lower at 5 to 10 years
• Complex CGI diagrams may overwhelm beginning readers who need simple pages
• Reading age is marked as from customers
• Focuses on visual spreads rather than sustained narrative reading

3

Mysteries of the Universe by Gater

Will Gater·9.7/10 Shelf Score

i

The Shelf Score runs from 9.2 to 9.8 and weighs fit for the reader or goal (35 points), contents and edition (25), value (25) and listed reading age or level (10, where the listing gives one), using only what the book listing states. How we pick ›

A storybook-style space encyclopedia introducing 100 celestial objects with photography and detailed artwork.

Check price on Amazon

Pros

• Covers 100 celestial objects with both photographic images and illustrations
• The listing states the jacket features gold foil, holographic foil, and metallic edges
• Grade level 2 to 4 and age range 6 to 8 fit younger elementary readers well
• Print length of 224 pages offers substantial reference material in an anthology format

Cons

• Storybook-style text may feel too simple for middle schoolers seeking deep technical data
• Reading age is marked as from customers
• Focuses on 100 individual objects rather than comprehensive systemic overviews
• Part of an anthology series, so readers may want companion volumes

4

Space Box Set by Wonder House Books

Wonder House Books·9.6/10 Shelf Score

i

The Shelf Score runs from 9.2 to 9.8 and weighs fit for the reader or goal (35 points), contents and edition (25), value (25) and listed reading age or level (10, where the listing gives one), using only what the book listing states. How we pick ›

A boxed set of six illustrated reference books answering science and astronomy questions for early learners.

Check price on Amazon

Pros

• Collection of 6 books divides space topics into bite-sized individual volumes
• Each book includes labeled diagrams, fun-fact sections, and a glossary of tough words
• Print length of 192 pages across the box set gives early learners manageable chunks
• Boxed set format makes it easy to share individual volumes among siblings or classmates

Cons

• The listing gives grade level 5 to 12 and reading age 10 to 17, while the description says ages 6 to 12
• Individual slim books provide introductory summaries rather than in-depth research
• Slim paperback volumes may show wear more quickly than a single hardcover encyclopedia
• Does not feature official NASA photography or named scientific contributors

5

Little Kids Space by Hughes

Catherine D. Hughes·9.5/10 Shelf Score

i

The Shelf Score runs from 9.2 to 9.8 and weighs fit for the reader or goal (35 points), contents and edition (25), value (25) and listed reading age or level (10, where the listing gives one), using only what the book listing states. How we pick ›

An early reference book introducing planets, the moon, and space exploration with simple text and colorful art.

Check price on Amazon

Pros

• Designed specifically for early learners with simple text and illustrations by David Aguilar
• Grade level Preschool to 3 provides an accessible entry point for beginning readers
• Structured into clear chapters moving from Earth and the moon out into the universe
• Print length of 127 pages is manageable for reading aloud with parents

Cons

• Publication date of October 9, 2012 makes it the oldest edition in this comparison
• Reading age of 3 to 6 years means older elementary kids will quickly outgrow the content
• Reading age is marked as from customers
• Does not cover recent space missions or newer astronomical discoveries from the past decade

As an Amazon Associate I earn from qualifying purchases.

More picks to compare

• Space: A Visual EncyclopediaKids who want NASA images, timelines and at-home space activities.Check on Amazon
• Space (Knowledge Encyclopedia)Young stargazers aged 8 and up, with diagrams and a glossary.Check on Amazon

Compare the picks

Book details as published on each listing, collected 16 October 2026.

How we scored them

The Shelf Score weighs fit for a young reader exploring astronomy, contents and edition, value, and the listed reading age or grade level. All five listings provide both a reading age and a grade level, though four mark the reading age as from customers, and the Wonder House Books listing features conflicting age recommendations between its spec table and description. How we pick explains the weights.

Scores run from 9.2 to 9.8: each book’s point total is placed on that range, so more points always means a higher score. Reading age or level counts on a list where at least one listing gives one, and a book whose listing gives none then scores zero on it. Where no listing gives one, the score is taken over the other 85 points. Books carry no warranty, so warranty is not scored.

How to choose the best space encyclopedia for kids

Check the reading age and grade level together

Listing levels come from different sources, with Amazon marking reading ages on four titles as from customers while grade levels generally reflect publisher data. When grade level and reading age align, as seen with the National Geographic Kids Space Encyclopedia at grade level 3 to 7, you can trust the target band. For a wider selection of reference volumes beyond astronomy, consult our guide to the best encyclopedia for kids.

Decide between a single comprehensive volume and a multi-book set

Format determines how a child interacts with astronomy content. A single reference like Knowledge Encyclopedia Space! offers 208 pages of comprehensive 3D cross-sections that invite browsing at a desk. In contrast, the six-book collection from Wonder House Books divides topics into slim individual booklets, making them less intimidating for younger children. For more choices across reading levels, browse our recommended middle grade books.

Before you buy

• Verify the publication date and edition: National Geographic Kids Space Encyclopedia is an updated 2nd edition from 2020, while the Little Kids title dates to 2012.
• Check customer reading ages against listed grade levels, especially on the Wonder House Books set where the spec table states grade level 5 to 12 but the description targets ages 6 to 12.
• Look at the format: DK’s Knowledge Encyclopedia Space! provides 208 pages in one heavy reference volume, whereas the Wonder House set divides 192 pages across six separate books.

Frequently Asked Questions

What age is the National Geographic Kids Space Encyclopedia for?

The listing gives grade level 3 to 7 and a customer-listed reading age of 6 to 10 years. With 208 illustrated pages, it is aimed at elementary and middle grade students.

Which space encyclopedia is best for preschoolers?

National Geographic Little Kids First Big Book of Space is designed for beginning learners, with a listed grade level of Preschool to 3 and a customer reading age of 3 to 6 years. Its 127 pages feature David Aguilar’s illustrations and clear chapters that introduce the solar system and moon.

How many books are in the Wonder House Books space set?

The Wonder House Books collection contains six individual books with a combined print length of 192 pages. Each book focuses on a single astronomy topic with diagrams, fun facts, and a glossary.

Still deciding? Our top pickSpace Encyclopedia by Aguilar

Check price on Amazon

Related lists

See every middle grade list and all kids and teens lists.

More lists: browse picture books, young adult books and our best book for kids guide.