How are astronauts pretected from solar radiation and extreme temperatures and pressures?

The gas giants, Jupiter, Saturn, Uranus and Neptune, have extreme pressure and extremely low temperature; the planet Venus has extreme pressure and extremely high temperature.

Extreme temperatures where?

More solar radiation results in higher temperature. A slight increase in solar radiation can cause a dramatic change in temperature on Earth.

Because space is a vacuum, heat is only transferred by radiation or by conduction through contact with something else. Having said that, the surface of the space suit may rise and fall quite a bit...

Venus because venus has a green house affect. Also because venus's atmosphere is so thick it traps in most all the sun's heat.