An Astronomer
a hubble space telescope
He looked through the telescope and was able to see Venus better.
The first person to look at the night sky with a telescope and record what he saw and try to make deductions from his observations was Galileo Galilei. Galileo had a difficult personality and he tried to assert that he was the only person allowed to make astronomical discoveries with a telescope, but, putting that aside, he was a serious scientist who made several important discoveries in physics.
because people would die
It would blind you to look at it.
A meteorologist.
look through a telescope at night
The answer to this is lost to prehistory. The first to look at the moon through a telescope would likely have been its inventors: Hans Lippershey, Zacharias Janssen and Jacob Metius, in 1608.
The first astronaut to see Mars through a telescope was most likely one of the Apollo astronauts who orbited the moon in the late 1960s and early 1970s. These astronauts had training in celestial navigation and would have had access to telescopes for observation during their missions. However, I could not find specific information on which astronaut was the very first to view Mars through a telescope while in space.
A paleontologist or a paleoecologist would most likely study Earth's past biosphere, focusing on the study of ancient life forms and ecosystems through the analysis of fossils and sedimentary records.
A scientist would most likely use a ruler or caliper to measure the length of a nail or other small object. These tools provide accurate measurements in centimeters or inches.
thermometer