References

BUYING GUIDE These are the best treadmills you can buy in every category, from NordicTrack x22i and Mobvoi Home Treadmill to Peloton Tread.

Buying Guide These are the best rowing machines you can buy in every category, from Concept2 RowErg and Ergatta Rower to Hydrow Wave.

BUYING GUIDE These are the best air purifiers for allergies you can buy in every category, from Levoit Core 600S and GermGuardian AC4825E to RabbitAir A3.

Buying Guide These are the best electric toothbrushes you can buy in every category, from Oral-B Genius X and Bitvae R2 to Waterpik Complete Care 9.0.

Reference Discover the complex history of the automobile, from early self-propelled vehicles to Karl Benz's invention of the first modern car, and explore the key innovators who shaped the cars we drive today.

Test your knowledge on our solar system, from the biggest and smallest planets to the behemoth mountain on Mars.

Basic information about the Artemis program's Space Launch System and Orion capsule.

BUYING GUIDE The best astrophotography cameras require excellent low-light capabilities — check out our favorite models to watch for this Black Friday.

BUYING GUIDE The best star projectors bring the wonders of the cosmos into your home — find the best models here so you're ready for Amazon Prime Day.

Unlock the night sky with the best binoculars for stargazing designed to capture stars, planets, and distant galaxies — our top picks for Black Friday Week.

The best binoculars for kids should be lightweight, compact, and easy to handle — explore top picks before Amazon Prime Day arrives next week.

Find the best binoculars for wildlife, stargazing, tracking athletes, or plane spotting — check out top picks ahead of Amazon Prime Big Deals Day next week.

The best telescopes offer an unparalleled view of the cosmos, and we've gathered our favorites just in time for Amazon Prime Big Deals Day.

BUYING GUIDE The best cameras for wildlife photography have impeccably accurate autofocus, a fast burst rate and sharp, detailed images — we've rounded up the best models.

An astronaut walks on the moon with a rover behind them

Think you know your constellations? See how many star groups you can name in 10 minutes and try to top the leaderboard.

There are 13 countries that sit on Earth's equator. Can you get them all in 5 minutes? If so, how fast can you do it?

BUYING GUIDE These are the best dehumidifiers you can buy in every category, from Honeywell TP50WK to LG Puricare.

Have a go at our killer whale quiz and find out if you'll make a big splash or a major fail.

For over 3,000 years, ancient Egypt was one of the most powerful civilizations on Earth, with an empire stretching across half a dozen modern-day countries. How much do you know about this iconic culture? Take our quiz to find out.