What is the journey time to our nearest galaxy?

Andromeda, the galaxy closest to the Milky Way, is about 2.5 million light years away. To travel in space, we need to achieve the speed of light, which is about 3,00,000 kilometres per second. Even at that great speed, it will take us about 2 million years (not 2.5 million years due to an effect called time dilation) to reach Andromeda.

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Invention of the thermometer

In about 1607, Galileo invented an instrument that could measure the rise of water in a glass tube with the rise in temperature. This instrument is called a thermoscope. Later, scientists modified it to add a scale to mark the rise of water. Subsequently, water was replaced with alcohol and mercury.

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