Spectroscopy — the use of light from a distant object to work out the object is made of — could be the single-most powerful tool astronomers use, says Professor Fred Watson from the Australian Astronomical Observatory. ... "It lets you see the chemicals being absorbed or emitted by the light source.
you will find your answer through this link
https://www.britannica.com/event/New-Deal
We know, by conservation of energy :

Therefore,

Putting given values, we get :

Therefore, the spring be compressed to 6.93 cm to send the ball twice as high.
Hence, this is the required solution.
Answer:
trigonometry (guessing)
Explanation:
ellipse: is the shape of an orbit : looks like an oval
periapsis : shortest distance between something like the moon and the planet its orbiting around like the earth
parallax is triangulation. like how gps works. looking at a star one day and then looking at it again 6 months later, an astronomer can see a difference in the viewing angle for the star. With trigonometry, the different angles yield a distance. This technique works for stars within about 400 light years of earth
https://science.howstuffworks.com/question224.htm
By comparing the intrinsic brightness to the star's apparent brightness we can calculate the distance of stars
1/r^2 rule states that the apparent brightness of a light source is proportional to the square of its distance.Jan 11, 2022
https://www.space.com/30417-parallax.html
alternative distance measurement for stars used by most astronomers is the parsec. A star with a parallax angle of 1 arcsecond has a distance of 1 parsec, or 1 parsec per arcsecond of parallax, which is about 3.26 light years
blossoms.mit.edu
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