If the scientist repeats the experiment over and over and gets the same results. Also if the scientist peer reviews the experiment to make sure there is no bias in his or her results.
Answer:
1992 (Early 1990s)
Explanation:
First of all, i would like to define an extrasolar planet as a planet that orbits a start that is not our own.
The first confirmed detections of extrasolar planets occured in the early 1990s (specifically 1992, some say 1995). The name of the first extrasolar planet is widely believed to be called Dimidium or 51 Pegasi b.
Extrasolar were searched by monitoring stars for slight dimming that might occur as unseen planets pass in front of them.
Answer:
They have same density
Explanation:
The density of an object is defined as
where
m is the mass of the object
V is its volume
Let's call 
and 
the mass and the volume of ball C, respectively. Therefore, the density of ball C is:
We know that the volume of ball C is 3 times the volume of ball D, so
And we also know that ball D has 1/3 the mass of ball C:
So, the density of ball D is:
Therefore, the two balls have same density.
An object seen in the water will usually appear to be at a different depth than it actually is, due to the refraction of light rays as they travel from the water into the air. This tutorial explores how fish, observed from the bank of a pond or lake, appear to be closer to the surface than they really are.
