Answer:
b. flat rotation curves in spiral galaxies
Explanation:
Dark matter accounts for majority of the matter in the universe (about 85%). It is considered to be composed of subatomic particles which are yet to be discovered. Dark matter cannot be observed because it does not emit light that can be detected. Only its gravitational effect is visible.
Astronomers when calculated the mass of the visible matter and tried to account for the observed speed of stars in the galaxy, there was a mismatch. To understand what caused this mismatch, astronomers gave name to the invisible matter as the Dark Matter.
The expected velocity of stars should decrease away from the near the center of the galaxy but a constant velocity of stars was observed that is a relatively flat rotation curve was obtained.
Thus, flat rotation curves in spiral galaxies in an evidence of Dark Matter.
Answer:
in regions where the temperature often drops below freezing at night
Explanation:
Weather is short term changes in the atmosphere. On the other hand climate describes what the weather is like over a long period of time.
B) Materials in Solution is NOT a process of a stream load
Streams must start somewhere. Streams are formed by having
sufficient water supply. The supply comes from rainfall and
underground reservoirs. The area that initiates the stream
supply is called the headwaters. Many times headwaters start
in the high elevations. As the water moves down through the
mountains, the stream’s pathway is formed. As streams evolve, the path of the stream starts to curve. The
curving of a stream channel is known as a meander. As meanders
develop, they become broader and larger. Eventually,
there are enough material deposits to form a blockage of two
meanders. This development causes the formation of an
oxbow lake.
<h2>
Answer: The greater the distance to a galaxy, the greater its redshift</h2>
When we talk about the <u>visible electromagnetic spectrum</u>, we know it starts in violet-blue and ends in red.
Now, in this context the astronomer Edwin Powell Hubble observed several celestial bodies, and when obtaining the spectra of distant galaxies he observed the spectral lines were displaced towards the <u>red</u><u> </u>(red shift), whereas the nearby stars showed a spectrum displaced to the <u>blue</u>.
From there, Hubble deduced that the farther the galaxy is, the more redshifted it is in its spectrum, and noted that all galaxies are <em>"moving away from each other with a speed that increases with distance"</em>, and enunciated the now called<u> Hubble–Lemaître Law</u>.
This means in the past the distance between two galaxies was smaller than at present, being this the proof that <u>the universe is expanding</u> (like a balloon expands when it is filled with air or another gas).
At this poitn it is important to stay clear that <u>the redshift is not produced by the relative movement of the galaxies with each other</u>. This effect is in fact, due to the <u>own expansion of the space</u> among the galaxies.
