A surprisingly large number of people in the world don’t believe that astronauts have walked on the Moon. They believe the Moon landing to have been a hoax. One argument they use is that if there are astronaut footprints on the Moon, we should be able to see them using a powerful telescope. The fact that we do not, they say, is evidence that they were never there. The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting the Moon. The LRO gets as close as 35 km to the Moon’s surface. The diameter of the camera’s primary mirror is 195 mm. If the camera is sensitive to optical light at a wavelength of 600 nm, show that it would not be able to spatially resolve a foot print of physical length 30 cm when it is 35 km above the Moon’s surface. Tip: You’ll need to calculate the angular size of the footprint, as seen from a height of 35 km. θ = S/D, where S is the physical size of the footprint and D = 35 km, is the angular size of the footprint in radians.
Stellar evolution
We may see thousands of stars in the dark sky. Our universe consists of billions of stars. Stars may appear tiny to us but they are huge balls of gasses. Sun is a star of average size. Some stars are even a thousand times larger than the sun. The stars do not exist forever they have a certain lifetime. The life span of the sun is about 10 billion years. The star undergoes various changes during its lifetime, this process is called stellar evolution. The structure of the sun-like star is shown below.
Red Shift
It is an astronomical phenomenon. In this phenomenon, increase in wavelength with corresponding decrease in photon energy and frequency of radiation of light. It is the displacement of spectrum of any kind of astronomical object to the longer wavelengths (red) side.
A surprisingly large number of people in the world don’t believe that astronauts have
walked on the Moon. They believe the Moon landing to have been a hoax. One argument
they use is that if there are astronaut footprints on the Moon, we should be able to see
them using a powerful telescope. The fact that we do not, they say, is evidence that they
were never there.
The Lunar Reconnaissance Orbiter (LRO) is a NASA robotic spacecraft currently orbiting
the Moon. The LRO gets as close as 35 km to the Moon’s surface. The diameter of
the camera’s primary mirror is 195 mm. If the camera is sensitive to optical light at a
wavelength of 600 nm, show that it would not be able to spatially resolve a foot print of
physical length 30 cm when it is 35 km above the Moon’s surface.
Tip: You’ll need to calculate the angular size of the footprint, as seen from a height of
35 km. θ = S/D, where S is the physical size of the footprint and D = 35 km, is the
angular size of the footprint in radians.
Step by step
Solved in 4 steps
