The planets move eastward against the background of fixed stars with the exception of Venus, Uranus and Pluto moving westward as seen in Earth's sky . This apparent retreating movement is called Retrograde motion. It is illusion created by Earth's movement going by outer planets in their respective orbits.
Answer:1.55 times
Explanation:
Given
First wavelength
Second wavelength
According wien's diplacement law

where 
T=Temperature
Let
be the temperatures corresponding to
respectively.



Thus object with
is 1.55 times hotter than object with wavelength 
Answer:

Explanation:
The acceleration of an object is the rate of change of velocity of the object.
Mathematically, it is calculated as:

where
u is the initial velocity
v is the final velocity
t is the time taken for the velocity to change from u to v
Acceleration is a vector, so it is important to also take into account the direction of the velocity.
For the particle in this problem, we have:
u = +48 m/s is the initial velocity (positive direction)
v = -92 m/s is the final velocity (negative direction)
t = 4.5 s is the time interval
Therefore, the average acceleration is

The best scenario to describe the doppler effect would be listening to the siren of a passing ambulance or fire truck
then it is coming towards you, the pitch is higher, it gets higher as it approaches and peaks as it gets right in front of you. then it drop at once when it passes you and continues to drop till it fades away. this is a classic descrption of the doppler effect