An open science encyclopedia

The universe, within reach

Science explained accurately, visually, and in plain language

Explore • Models • Simulations

Interactive exploration

Experience science through 3D models, sky maps and a journey across scales, from the observable universe down to our own planet.

🚀 Start here

The Solar System in 3D

Watch the planets move along their real orbits in three dimensions.

8 planets
Positions from NASA Horizons

Open the model

The zoom journey

Go from the observable universe down to Earth in one continuous run.

4 scale steps
Universe → Earth

Start

Earth from L1

Full-disk images of Earth captured from the L1 Lagrange point by NASA's DSCOVR spacecraft.

NASA EPIC imagery
One full rotation a day

View live

⭐ Featured

The sky map

Find galaxies, nebulae and planetary surfaces on real survey imagery.

Real sky imagery
18 suggested targets

Open the map

The Milky Way in 3D

Explore the structure of our galaxy and where the Solar System sits inside it.

4 spiral arms
Where the Sun sits

Explore

Map of the Universe in 3D

Travel through the cosmic web — matter filaments, galaxy clusters and vast empty voids.

Filaments and voids
Large-scale structure

Explore

Featured

Our most carefully edited pieces this week

See all articles

The Solar System

The Sun: the reactor that holds a system together

The Sun holds 99.86% of the Solar System's mass and fuses 600 million tonnes of hydrogen every second. All light, weather and life on Earth trace back to it.

3 min read4

The Solar System

Earth: the only living world we know

Liquid water, an oxygen-rich atmosphere, a protective magnetosphere and plate tectonics - four rare conditions on one world.

1 min read4

The Solar System

Mars: the red planet and the water question

It once had rivers, lakes and perhaps an ocean. Understanding how Mars lost its water is understanding how a world stops being habitable.

1 min read1

Stars and Galaxies

Black holes: where the geometry of space collapses

Not cosmic vacuum cleaners but regions where spacetime curves so sharply no path leads out. From theory to the first image in 2019.

3 min read6

Sleep

What deep sleep does to your memory

Your brain does not rest while you sleep. It replays, filters and moves the day's learning into long-term storage while clearing metabolic waste.

3 min read8

Explore today

One article to start with each day, plus a few unexpected detours.

Random article

Today's article

Physiology and Metabolism

The Gut, the Microbiome, and the Power of the Second Brain

The digestive system extends beyond its role in food processing. Often termed the "second brain," the gut contains a complex, autonomous network of neurons known as the enteric nervous system (ENS), which possesses the capacity to function independently of the central nervous system.

2 min read1

Quick detours

Browse by field

Pick a field and go deep

Cosmos

From the Sun next door to galaxies billions of light-years away — space, astronomy, and humanity's journey beyond Earth.

35 articles

Health

How the human body works, and what the evidence actually says about sleep, nutrition, immunity and exercise.

4 articles

Physics

From quantum mechanics to relativity - the ground rules everything else obeys.

9 articles

Biology

Cells, DNA, evolution and the diversity of life on Earth.

4 articles

Earth and Climate

Geology, oceans, atmosphere and a climate system in transition.

5 articles

Chemistry

Elements, bonds and reactions — how matter combines and changes.

0 articles

Technology and Engineering

Machines, materials, energy and computing — what humans build with scientific knowledge.

0 articles

New in the library

Freshly added to the library

Featured

Nutrition

How Does Intermittent Fasting Affect the Gut Microbiome?

Intermittent fasting (IF) influences not only caloric intake but also the ecosystem of the gut microbiome. Research suggests that distinct windows of eating and fasting may alter the composition and metabolic activity of these trillions of microorganisms.

2 min read1

Physiology and Metabolism

The Gut, the Microbiome, and the Power of the Second Brain

2 min read1

Space Exploration

What Would Happen to a Human in Space Without a Spacesuit?

Outer space is an extremely hostile environment for the human body. The absence of breathable air, near-zero atmospheric pressure, extreme temperatures, and hazardous radiation make it impossible for humans to survive for long without a protective suit.

3 min read2

Space Exploration

Outer Space: A Near-Perfect Vacuum

By definition, a vacuum is a space nearly devoid of matter. Outer space is the largest known natural vacuum, characterized by an extremely low density of matter.

3 min read4

Mechanics

The Science Behind the "Dropping" Sensation During Velocity Changes

The sensation of being pulled backward during acceleration or thrown forward during sudden braking is not caused by a mysterious force, but is the result of inertia—an inherent property of all objects with mass.

2 min read2

Mechanics

Why don’t we feel Earth’s rotation?

Each morning, the Sun does not actually "rise" from the horizon. Instead, Earth’s rotation carries our location into the sunlit region. At the equator, the planet’s surface moves at approximately 1,670 km/h, faster than most commercial aircraft. Why, then, do we not perceive this motion, and why are we not flung into space?

2 min read3

Ask anything about science

An AI assistant that answers from Sciencepedia's own library and always cites its sources.

Start chatting

Try asking