After what are the Tropics of Capricorn and Cancer named?

The Tropic of Cancer was named because at the time of its naming, the sun was positioned in the Cancer constellation during the June solstice. Likewise, the Tropic of Capricorn was named because the sun was in the constellation Capricorn during the December solstice. The naming took place about 2000 years ago, and the sun is no longer in those constellations at that time of year. At the June solstice, the Sun is in Taurus, and at the December solstice, the sun is in Sagittarius.