The James Webb Space Telescope
JWST Part 2: How to Build a Time Machine
Nerd Out
-
About
Building a better worldWe are increasing the number of engineering innovators and leaders who will make what’s next for the world even better.
-
Programs
Driving changeInspiring the next generation of engineers to build a more creative, innovative, sustainable world.
-
Locations
GE businesses around the world are inspiring young mindsFind city profiles, activities and how to join.
-
News
Latest news & updatesRead all news, updates, and happenings from the Next Engineers initiative.
Cities navigation
GE businesses around the world are inspiring young minds
Find city profiles, activities and how to join.
Inspiration navigation
Driving change
Inspiring the next generation of engineers to build a more creative, innovative, sustainable world.
News navigation
Latest news & updates
Read all news, updates, and happenings from the Next Engineers initiative.
Resources navigation
Explore all resources
Find the tools that you need to run a successful Next Engineers program, including communication collateral and templates, student and volunteer outreach materials, student activity guides, engineering challenges, and Monitoring & Evaluation resources.
Building a better world
We are increasing the number of engineering innovators and leaders who will make what’s next for the world even better.
Challenge Yourself
Find activity guides and resources to help you as students, parents, and teachers stay curious and build worlds that haven't even been thought of yet.
A Time Machine
The James Webb Space Telescope is designed to see objects in space further away than any other telescope ever, thus seeing further back in time than we have ever done. Scientists hope to see back in time almost to the moment of the Big Bang, the birth of the universe. This was about 13 billion years ago when the very first stars and galaxies were born.
It will only be able to do this by collecting and concentrating the tiny amounts of light that come from these very distant and very dim objects. But to collect enough light to make a clear image you need an enormous 6.5 m (21 feet) wide mirror. That is over two stories high. The Hubble Space Telescope’s primary mirror is only 2.4 m (7.87 ft) wide.
Have a think primary
Have a think
The James Webb primary mirror has 18 regular hexagonal segments, each 1.32 m flat to flat.
In a regular hexagon all the sides are equal in length. Can you calculate the actual surface area of the James Webb primary mirror?
HINT: The relationship between the distance flat to flat (f) and the length of the sides (s) of the hexagon is f = 1.732 x s
Mirrors: Hubble vs. JWST
full-width
Overall, the primary mirror is shaped like a large satellite dish. It is parabolic. Parabolas are very good at reflecting all the light they receive to a single spot, the focal point.
Have a think primary
Have a think
What's a Parabola?
A diagram of a parabolic reflector, reflecting light rays to the focal point, F. Image by Filu released under a GNU Free Document license.
Play with this simulation of a parabolic reflector and see if you can figure out why all the light rays are reflected to the same spot, the focal point.
What other objects have you seen that are parabolic reflectors?
Find out more about parabolic reflectors.
full-width
© 2025 FHI360
