Hello,
Astronauts have only traveled to the Moon or spent time orbiting the Earth. Astronauts have never been to any of the other planets in the solar system. Astronauts have also never traveled close to the Sun. It may be possible for us to send astronauts to Mars in the near future. However, sending astronauts to the planets that are closest to the Sun (Mercury and Venus) or actually to the Sun itself will not be possible anytime soon, and it might never be possible. The reason for this is that manned space travel is extremely expensive, difficult, and dangerous. The conditions on the planets Mercury and Venus are not hospitable for humans. Astronauts cannot travel close to the Sun because their spacecraft would be damaged by the intense heat and radiation, and they would probably be killed.
Even though humans cannot go to these places, we can still send unmanned missions to Mercury and Venus, and observe the Sun from a safe distance using unmanned satellites.
Kris