> The Andromeda galaxy will never appear as bright as in that image, not matter how close it is. As things get closer they do, of course, cast more light on us, but that light also comes from a larger solid angle, which means when we look at them, the brightness (per area) remains constant.
The expressions "look so bright" and "appear even larger" refer to a change in our perception of Andromeda, i.e., the resolution of your eyes. In the distance, the bright objects blur with the dark background, so that we do not perceive a lot of structure. Closer in, the contrast increases so that we can distinguish brighter from darker structures. This is analogous to the fact that with binoculars we can see stars that we cannot see with the naked eye.
When a distant object gets closer, the area that the object occupies in our field of view becomes larger. So while its brightness under the same angle remains the same, its overall brightsness increases. Think of someone approaching with a torchlight from 100 meter to one centimeter from your eye.
This is what can be seen in the eight pictures in the article. The little Andromeda spot and its halo on the first picture is as bright as Andromeda in average in the subsequent pictures; only that it becomes larger. The 7th and 8th picture show the core of Andromeda and the Milkyway together and without the darker surroundings. This is the reason why the overall brightness of the pictures is higher. (Or in the binoculars analogy: Don't look with binoculars into the sun!)
The expressions "look so bright" and "appear even larger" refer to a change in our perception of Andromeda, i.e., the resolution of your eyes. In the distance, the bright objects blur with the dark background, so that we do not perceive a lot of structure. Closer in, the contrast increases so that we can distinguish brighter from darker structures. This is analogous to the fact that with binoculars we can see stars that we cannot see with the naked eye.
When a distant object gets closer, the area that the object occupies in our field of view becomes larger. So while its brightness under the same angle remains the same, its overall brightsness increases. Think of someone approaching with a torchlight from 100 meter to one centimeter from your eye.
This is what can be seen in the eight pictures in the article. The little Andromeda spot and its halo on the first picture is as bright as Andromeda in average in the subsequent pictures; only that it becomes larger. The 7th and 8th picture show the core of Andromeda and the Milkyway together and without the darker surroundings. This is the reason why the overall brightness of the pictures is higher. (Or in the binoculars analogy: Don't look with binoculars into the sun!)