Question

What is meant by 'The sun enters a nakshatra'? It is said that in the rainy season the sun enters the Mrug nakshatra. What does it mean?

Answer 1

A constellation or nakshatra, is present behind the sun, which gets hidden because of the bright sunlight. So, when we look up in the sky, we are actually seeing both the sun and the constellation behind it. Thus, when the Earth changes position, it appears to an observer on Earth as if the Sun has moved from its position and is entering a new constellation or nakshatra.
The Sun entering the Mrug Nakshatra in rainy season means that Mrug Nakshatra or Orion is behind the Sun.