How to edit science explainer videos: stock, animation and real imagery

How do you edit a science explainer video?

Edit a science explainer by splitting the script into concepts, then choosing real imagery, simulation, animation or stock for each line. Label anything illustrated, give every big number a comparison the eye can read, build diagrams step by step with the voice, grade stock to match the animation, and design sound for subjects that make none.

Plainly: I haven't edited a science or space explainer for a client yet. This guide is how I would edit one, based on the closest work I do (narrated documentaries where every line needs a visual, including maps and diagrams drawn in-house when no licensed one fitted) and on measurements of three large science channels taken today.

The steps:

1. Split the script into claims and concepts.
2. Pick the visual tier for each line.
3. Label what is real and what is illustrated.
4. Make scale readable.
5. Build diagrams one idea at a time, with the voice.
6. Make stock and animation look like one video.
7. Design sound for things that make no sound.
8. Pace for explanation, then for awe.

How long are science and space explainers?

I read the 12 most recent uploads of three large science and space channels on October 18, 2026.

The three styles produce three length profiles. Kurzgesagt is the most predictable: the middle half of its videos sits between 13.1 and 15.2 minutes. Astrum runs longer (middle half 22.6 to 31.9 minutes) and 2 of its 12 latest uploads pass an hour, including a two hour "Earth's Entire Existence In One Video". melodysheep's median is misleading on its own: its list mixes trailers of one to two minutes with documentaries of 28 to 108 minutes. A channel built on narration over imagery can go long cheaply; a fully animated one pays for every second, and its length shows it.

Step 1: Split the script into claims and concepts

Read the script and mark every line as one of two kinds:

• A claim is something that exists or happened: a planet, a telescope image, a discovery, a date. It wants real imagery.
• A concept is a mechanism or an idea: how gravity bends light, why a moon is cold, what a timeline of the universe looks like. It wants a diagram or an animation.

In a typical 15 to 25 minute explainer, most lines are claims and only four to eight are true concepts. Those few are where the viewer either understands or leaves, so they get the most edit time. Knowing the count before starting also tells the channel how much animation the episode really needs, which is the biggest cost decision in this format.

Step 2: Pick the visual tier for each line

For each line, take the most real option that honestly shows it:

For space subjects, NASA is the deepest free archive, and its media usage guidelines are worth reading once in full. NASA content is generally not subject to copyright in the United States, but the logos and insignia are protected, current astronauts' names and likeness cannot be used on commercial products or advertising, and third-party images in its collections are marked with the copyright holder's name and need that holder's permission. I log every file with its page link and credit, the same license log I keep on documentaries.

Step 3: Label what is real and what is illustrated

Science viewers are quick to call out an illustration passed off as a photo. A short caption fixes it: "Artist's impression", "Simulation", "Illustration, not to scale". Put it in the same corner and size every time, on screen for the whole shot. On the documentaries I edit the matching rule is that a recreation never carries a name label as if it were the real person; in science it is the same idea applied to planets and molecules.

The caption also frees the edit. Once the viewer knows a shot is an illustration, it can be bold, colourful and dramatic without anyone feeling misled.

Step 4: Make scale readable

Science scripts are full of numbers no one can picture: light years, nanometres, billions of years. Saying them is not enough. Give each one a comparison the eye can read:

• Side by side objects. The planet next to Earth, the cell next to a hair, both drawn to the same scale.
• A zoom chain. Start at something familiar and zoom out or in step by step, with a small label at each step. Three or four steps are enough; ten turns into a screensaver.
• A counter or timeline bar for time: a year counter ticking, or a single bar where human history is a sliver at the end.
• A number card with the figure written the way the voice says it, plus one comparison line.

Keep units consistent with the narration. If the voice uses kilometres, the screen does not switch to miles.

Step 5: Build diagrams one idea at a time, with the voice

The concepts marked in step 1 get diagrams, and the rule for every one is the same: add one element per idea, at the moment the voice says it. A diagram of how a black hole bends light starts with the black hole alone, then a straight line of light, then the bend, then the observer. Shown complete from the start, it becomes a puzzle the viewer solves while the narrator talks past them.

On The Tenerife Disaster, maps and diagrams were only about 3% of the material, but they carried the spatial part of the story, and I drew them in-house when no free diagram fitted: some free ones on Wikimedia Commons were labelled in German or Italian, which does not work in an English video. Three practical habits:

• Label parts with words the script uses, no more.
• Hold the finished diagram for a second or two after the explanation ends.
• Reuse the same diagram when the script returns to the idea, so the viewer recognises it.

Step 6: Make stock and animation look like one video

The most common look problem in mixed science videos is that each source looks like a different video: crisp animation, warm stock, noisy archive photos. Bring them together:

• Grade toward the channel's palette. If the animation is cool blues and oranges, push stock that way too.
• One frame rate and resolution. Conform everything to the timeline's frame rate and scale low resolution imagery with care, or frame it as an inset rather than stretching it.
• A shared texture. A light grain or vignette over everything hides the joins.
• Matching movement. If the animation moves slowly, stock with fast handheld camera feels like an ad break.

Stock should stay in its lane: generic scenes only, the same rule I apply on documentaries, where stock never pretends to be archive. The stock footage guide has the details on matching and avoiding repeats.

Step 7: Design sound for things that make no sound

Space is silent and molecules do not whoosh, yet a science video with no sound design feels flat. Treat sound as part of the visual style:

• Low rumbles and tones for large objects and slow motion; light, short sounds for small things.
• Sound on reveals and zoom steps, so scale has a feeling.
• Music that follows the arc: curious during the explanation, wide and slow for the moment of awe.
• Everything under the voice. Check the mix in the free YouTube Loudness Check, and see how loud background music should be under a voiceover.

Step 8: Pace for explanation, then for awe

Science videos have two speeds, and the edit has to switch between them. During an explanation, visuals change with the ideas, often every few seconds, and nothing distracts from the diagram. At the payoff (the scale of the universe, the age of the Earth), the pace can slow right down: a long shot, music up, voice silent for a beat. That contrast is what makes the slow moment land. Without it, either the whole video feels rushed or the whole video feels like a screensaver.

Measure one video of the reference channel you want to match: how often the picture changes in explanation sections versus payoff sections. Then hold your cut to that. On the faceless documentaries I edit, writing those numbers down before the first cut is what keeps revision rounds short.

Common mistakes in science video editing

1. Illustrations with no label, which invites "this is fake" comments.
2. Diagrams shown complete instead of built with the narration.
3. Big numbers with no comparison, said and forgotten.
4. Stock standing in for a specific object: a random galaxy for a named one, a generic rocket for a named mission.
5. Every source with its own look, so the video feels stitched together.
6. Agency logos used as if the agency endorsed the video.
7. No slow moment, so the payoff never feels bigger than the rest.

For the rest of the faceless workflow (voiceover cleanup, a visual per line, the license log), see how a faceless YouTube video gets edited. For channels that teach, my education YouTube editor page covers on-screen citations.

Science explainer editing FAQ

How long should a science explainer video be?

It depends on the style. On October 18, 2026, the 12 latest uploads of Kurzgesagt had a median of 14.2 minutes and a narrow spread (13.1 to 15.2 minutes for the middle half), while Astrum ran a median of 26.1 minutes with two videos over an hour. Fully animated explainers tend to be shorter because every second costs more to make.

Can you use NASA images and videos in a monetized YouTube video?

NASA says its content is generally not subject to copyright in the United States, but its logos and insignia are protected, identifiable astronauts may need permission for commercial uses, and third-party images in NASA collections are marked with the copyright holder. Check each file's own page and the NASA media usage guidelines before using it.

Do you need animation to make a science video?

No, but most science scripts have a few concepts that only a diagram can explain. A channel can run on real imagery, simulations and stock, with simple animated diagrams for the four or five ideas per video that need them.

Should space videos have sound effects?

Space is silent, but most space channels still use designed sound: low rumbles, tones and textures that give scale and motion a feeling. Keep it a deliberate style choice, keep it under the voice, and stay consistent across episodes.

How do you show something that has never been photographed?

Use an illustration, simulation or animation and label it as such on screen, for example "artist's impression". The label costs nothing and protects the channel from the comment that the image is fake.

Sources

Channel lengths: the 12 most recent uploads of Kurzgesagt, Astrum and melodysheep, read from their public video pages on October 18, 2026. Imagery rules: NASA images and media usage guidelines, read on October 18, 2026. The Tenerife diagrams are from my delivered edit for The Interpreter; the case study is here.