Answer: it is expanding in size
Explanation: In 1929, Edwin Hubble provided the first observational evidence for the universe having a finite age. Using the largest telescope of the time, he discovered that the more distant a galaxy is from us, the faster it appears to be receding into space. This means that the universe is expanding uniformly in all directions.
(hubblesite.org)
Secondly, There's a phenomenon called red-shifting, that causes the light from objects moving away from you to shift towards the red end of the spectrum, whereas objects moving towards you have their light shifting towards the blue end of the spectrum. This same phenomenon can be observed in the change in the sound of an ambulance siren, as it passed you. The pitch of the sound is different, when it moves towards you and away from you.By observing the light spectrum from distant stars and galaxies, astronomers have discovered, that the further away an object is, the faster it moves away from us, which shows us, that the Universe is expanding.