In spring, a bright star appeared at 240 degrees southwest. What is this?

Because there are no specific geographical coordinates, the meaning of passing the question is roughly Jupiter.

Seen from the earth, Jupiter's apparent magnitude can reach as high as -2.94. And you can already shine the shadow on the ground. Jupiter is the third celestial body with average brightness in the night sky after the moon and Venus (Mars can briefly surpass Jupiter's brightness at some points in its orbit).

Related information:

Jupiter's main component is hydrogen, but helium, which accounts for only one tenth of the molecules, accounts for a quarter of the total mass; It may have a rock core and heavy elements, but there is no clearly defined solid surface. Because of its rapid rotation, Jupiter's appearance is oblate. The atmosphere is divided into different zones and regions according to latitude, and there are turbulence and storms at the junction.

The most obvious example is the Great Red Spot, which is a huge storm that has not stopped since the telescope first saw it in the17th century. Jupiter is surrounded by a weak planetary ring and a strong magnetosphere, including four Galileo satellites discovered in 16 10, and 79 satellites discovered in 20 19+02. Ganymede is the largest one, and its diameter is larger than that of Mercury in the planet.