historyWikipedia1734 · Jaipur, India

Jaipur's Jantar Mantar holds 19 stone instruments built by Sawai Jai Singh to observe the sky without telescopes

the gist

The Jantar Mantar in Jaipur is a collection of 19 astronomical instruments built by the Rajput king Sawai Jai Singh, founder of Jaipur, and completed in 1734. The instruments measure positions in the sky using three main systems: horizon-zenith, equatorial and ecliptic coordinates. They work by sight alone, using the naked eye. The monument features the world's largest stone sundial, which tells time from the sun's shadow. It reflects the Ptolemaic positional astronomy shared by many civilisations. The site was damaged in the 19th century and later restored under British supervision.

how it works

A sundial tells time by casting a shadow whose position changes as the sun moves across the sky. Large stone instruments like these let astronomers read angles precisely without telescopes.

so what

The observatory shows the sophistication of Indian astronomy in the early 18th century, and its instruments can still be used to read the sky. It is a UNESCO World Heritage Site, valued for its scientific and cultural importance.

fun fact

Sawai Jai Singh built several observatories across northern India, including one in Delhi.

more on this

key facts

Country
India
Located in
Jaipur
Area
2 km²
Founded
1738

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Image: Wikimedia Commons