Library branch

Astronomy & Space

How the sky was read and the universe measured.

11 pieces

Tool The Starlight Timetable — When Did That Light Leave? Choose an object and see when its light set out — and what was happening on Earth that year. The light from the pole star left in the middle of the Joseon dynasty; a letter between the Weaver and the Herdsman would take thirty years. Tool The Cosmic Calendar — 13.8 Billion Years in One Year Compress 13.8 billion years into a single year: one day is 37.8 million years, one second is 437. Earth appears in September and our species on the evening of 31 December — and zooming in never widens our share.

How Much Do You Know About Light? The Sun You See Is Eight Minutes Old Flick a switch and the room lights at once, which is why light was long thought infinitely fast. It is not. Light arrives late. 2 questions
How Much Do You Know About Light? Why Is the Night Sky Dark? If stars were endless, every line of sight would end on one and the night sky would blaze. It is black instead — and that darkness is evidence that the universe has an age. 1 questions
How Much Do You Know About Light? The First Light of the Universe Is in This Room The snow on an old analogue television. A small part of that noise set out 13.8 billion years ago. The men who caught it first blamed pigeon droppings. 1 questions
How Much Do You Know About Light? Light Grows Old — What Recedes Turns Red A siren is high approaching and low receding; light from what recedes is pushed toward the red. And it holds in every direction we look. 1 questions
How Much Do You Know About Light? Where Light Cannot Leave Make something massive enough and packed tightly enough, and leaving it would require going faster than light. Nothing is, so nothing does. 2 questions
How Much Do You Know About Light? Every Beam Carries the Star's Name Tag We have never been to a star, yet we know what stars are made of. Helium was found in the Sun before it was found on Earth. 2 questions
Where the Formulas Came From How the Distance to the Moon Was Measured There is only one way to measure a distance you cannot reach with a tape: make a triangle. With that single method, people worked out the distance to the Moon, then the Sun, then the stars, then galaxies. 3 questions
Where the Formulas Came From How the Size of Our Galaxy Was Measured Triangulation runs out at the nearest stars; beyond that the angles are too small to measure. Another method was needed, and it came from someone examining photographic plates at the Harvard Observatory. 3 questions
Science on the Screen Contact — Why the Message Begins with Prime Numbers A series following the science a film borrows — not to check its homework, but to see which theory was taken up and how it was turned into a story. First: Contact, a film about mathematics as a common tongue, listening to the sky by radio, curved space, and what we may do when there is no evidence. 3 questions
Wrong, and Useful Anyway Geocentrism — Fourteen Centuries of Correct Predictions The sun rises and sets, the stars wheel overhead, and the ground does not stir. Geocentrism was the world as seen, and the calculations built on it worked for fourteen centuries. What brought it down was not a better fit to the data — Copernicus was not more accurate. 8 questions
Science in Korea — What Is Being Built Here To Look at a Star Is to Look at the Past The starlight you look up at tonight did not set out tonight. Some left a few years ago, some a few centuries. So the night sky is not one photograph but many different pasts overlaid. The astronomy institute and the citizens' observatory in Daejeon both work on that screen. 4 questions

Routes through this branch

How Much Do You Know About Light? →Where the Formulas Came From →Science on the Screen →Wrong, and Useful Anyway →Science in Korea — What Is Being Built Here →