1.The Hubble Space Telescope is a well-known satellite. It was launched into space in 1990. It is in orbit 380 miles above Earth. Hubble takes photos of our solar system and faraway galaxies. A galaxy is a huge group of stars, dust, and gas. Over the years, Hubble has taught scientists a lot about space. What is the appropriate unit for measuring the distance to other galaxies? A. Miles
B. Astronomical units
C. Kilometers
D. Light years

Scientists use laser range-finding to measure the distance to the moon with great accuracy. a brief laser pulse is fired at the moon, then the time interval is measured until the "echo" is seen by a telescope. a laser beam spreads out as it travels because it diffracts through a circular exit as it leaves the laser. in order for the reflected light to be bright enough to detect, the laser spot on the moon must be no more than 1.0 km in diameter. staying within this diameter is accomplished by using a special large-diameter laser. part a if λ = 540nm , what is the minimum diameter of the circular opening from which the laser beam emerges? the earth-moon distance is 384,000 km. express your answer to two significant figures and include the appropriate units.

What you see with your eyes is a form of energy. a. light b. heat c. chemical d. electrical

Awave has a wavelength of 7 mm and a frequency of 19 hertz. what is its speed?