Eyes in the sky: The Wknd Puzzle by Dilip D’Souza
Mark the launch of the James Webb Space Telescope with a multi-mirrored Einstein puzzle that should lead you to an observer millions of miles away.
A truly remarkable scientific instrument soared into space on Christmas Day: the James Webb Space Telescope (JWST). It promises all kinds of discoveries about the universe, and has astronomers the world over tingling with excitement. This puzzle is my small tribute to the JWST, but to scientific endeavour more generally.

JWST is not the first space telescope. Two others are up there, the Kepler (KST) and the Hubble (HST). Imagine yourself about two years from now, when JWST starts delivering on its promise, and see if you can use these clues to answer the questions that follow. (If you know something about these instruments, which is more than likely, don’t draw on that knowledge to solve this puzzle.)
* The telescope that’s 137 million km away and the JWST were both launched in the 21st century.
* The telescope that confirmed finding 3,000 “exoplanets” (planets outside our solar system) has the smallest mirror, just 1.4 metres across.
* The 6.5 metre mirror is not on the HST.
* Either the telescope that’s 1.5 million km away or the HST has observed previously unknown and extremely young galaxies that are only a few million years old.
* The KST is not the telescope known for confirming the existence of black holes; that telescope is the closest to the Earth of the three, only 540 km away.
* The largest mirror is on the telescope that found the very young galaxies.
* The HST was launched in 1990.
Questions:
* Which telescope has a mirror that’s 2.4 metres across?
* How far away is the telescope known for finding 3,000 exoplanets?
Scroll down for the answers.
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Answers:
* The Hubble Space Telescope has the 2.4 metre mirror.
* That’s the Kepler Space Telescope, which is 137 million km away.