The magnificent seven

Copied!

👇 Get new sketches each week

A worthy ball juggling challenge next time you’re messing around with a football.

Published 18 Sep 2013

Get the book!

Big Ideas Little Pictures

Prefer to listen?

Try the podcast

🎉 Help keep Sketchplanations ad-free 🎉 Keep this ad-free 🎉 Help keep Sketchplanations ad-free by supporting me

Keep exploring

Looking back in time as we look to the stars: A visual explanation of how light from the Moon, Sun, stars, and galaxies shows us the past because light takes time to travel.

Looking Back in Time: The Speed of Light and the Night Sky

Eponym

List of common sushi types, explained with names and pictures — a visual guide including nigiri, sashimi, maki rolls (hosomaki, futomaki, uramaki, temaki), inari, chirashi, and temari.

Types of Sushi: Decoding a Sushi Menu

Everyone's a geek about something with people geeking out on many different activities

Everyone's a Geek About Something — Revised and Expanded

Everyone’s a geek about something

Everything is aiming

The speed of light is a mighty ~300,000 km/s. But even at that speed, because the distances in space are so vast, sometimes it has to settle in for the ride. When we see the light from a distant star or galaxy, we're not seeing it as it is now—we're seeing it as it was when the light first left on its journey to Earth. Why Looking at Stars Is Like Looking into the Past When you hear a thunderclap after seeing lightning, you know that you're hearing something that happened some time ago. Looking into the night sky is similar—except here, it's light that causes the delay, not sound. Take the moon, for instance. At a little under 400,000 km away, light that has reflected off the moon takes around 1.3 seconds to reach us. But the sun is much further. At around 150 million km away, it takes a little over 8 minutes for light from the sun to reach us. So what we are seeing at the sun, for example, a solar flare, happened 8 minutes ago. (The distance from the sun to Earth is called 1 AU - Astronomical Unit). As soon as you look at more distant objects, you realise that looking up at the night sky is looking way back in time. To measure these distances, we use light years—the distance light travels in one year. So, the number of light years an object is away from us is how far back in time we are seeing. Our nearest star system is Proxima Centauri at around 4.24 light-years away. What we see on Proxima Centauri happened over four years ago. Here are a few stars you can spot at night (in the northern hemisphere) and how long ago the light from each started its journey: Polaris (the North Star): 433 years ago, around 1590 AD Pleiades (Seven Sisters): 444 years ago, around 1580 AD Betelgeuse: 548 years ago, around 1480 AD Put another way, if you were in Betelgeuse right now, you’d be looking at light from our sun around the time Leonardo da Vinci was pioneering sketchplanations. The Andromeda Galaxy, the nearest spiral galaxy to our Milky Way, is a staggering 2.5 million light-years away. This means the light we see from Andromeda today set off on its journey 2.5 million years ago — around the beginning of the Pleistocene, the most recent ice age era, when early mammoths and sabre-toothed cats were emerging. Seeing the Early Universe As we look with increasingly larger telescopes at more distant objects, scientists gather clues about the Universe's earliest days. The farther we look, the farther back in time we see. In 2024, the James Webb telescope detected a galaxy so far away that the light we see started travelling when the Universe was just 2% of its current age. So, as you look up in the sky, it's also like looking at a map of different times. Crazy. Related Ideas to Looking Back in Time Find the North Star Use the Southern Cross to find south Solar system planets: how big is the solar system? Redshift Orbit Point Nemo Antipodes Super moon The Overview effect Comets, Asteroids, Meteors, and Meteorites: know your space objects The Flash-to-Bang Method for estimating the distance of lightning The Doppler effectThe speed of light is a mighty ~300,000 km/s. But even at that speed, because the distances in space are so vast, sometimes it has to settle in for the ride. When we see the light from a distant star or galaxy, we're not seeing it as it is now—we're seeing it as it was when the light first left on its journey to Earth. Why Looking at Stars Is Like Looking into the Past When you hear a thunderclap after seeing lightning, you know that you're hearing something that happened some time ago. Looking into the night sky is similar—except here, it's light that causes the delay, not sound. Take the moon, for instance. At a little under 400,000 km away, light that has reflected off the moon takes around 1.3 seconds to reach us. But the sun is much further. At around 150 million km away, it takes a little over 8 minutes for light from the sun to reach us. So what we are seeing at the sun, for example, a solar flare, happened 8 minutes ago. (The distance from the sun to Earth is called 1 AU - Astronomical Unit). As soon as you look at more distant objects, you realise that looking up at the night sky is looking way back in time. To measure these distances, we use light years—the distance light travels in one year. So, the number of light years an object is away from us is how far back in time we are seeing. Our nearest star system is Proxima Centauri at around 4.24 light-years away. What we see on Proxima Centauri happened over four years ago. Here are a few stars you can spot at night (in the northern hemisphere) and how long ago the light from each started its journey: Polaris (the North Star): 433 years ago, around 1590 AD Pleiades (Seven Sisters): 444 years ago, around 1580 AD Betelgeuse: 548 years ago, around 1480 AD Put another way, if you were in Betelgeuse right now, you’d be looking at light from our sun around the time Leonardo da Vinci was pioneering sketchplanations. The Andromeda Galaxy, the nearest spiral galaxy to our Milky Way, is a staggering 2.5 million light-years away. This means the light we see from Andromeda today set off on its journey 2.5 million years ago — around the beginning of the Pleistocene, the most recent ice age era, when early mammoths and sabre-toothed cats were emerging. Seeing the Early Universe As we look with increasingly larger telescopes at more distant objects, scientists gather clues about the Universe's earliest days. The farther we look, the farther back in time we see. In 2024, the James Webb telescope detected a galaxy so far away that the light we see started travelling when the Universe was just 2% of its current age. So, as you look up in the sky, it's also like looking at a map of different times. Crazy. Related Ideas to Looking Back in Time Find the North Star Use the Southern Cross to find south Solar system planets: how big is the solar system? Redshift Orbit Point Nemo Antipodes Super moon The Overview effect Comets, Asteroids, Meteors, and Meteorites: know your space objects The Flash-to-Bang Method for estimating the distance of lightning The Doppler effect

Newer

RRandom

Older

As an Amazon Associate I earn from qualifying purchases.