1The astronomy club set up telescopes on the hill after sunset.
2Looking at distant galaxies is literally looking back in time.
3Their light has travelled for millions of years to reach us.
4Our galaxy alone contains hundreds of billions of stars.
5The observable universe holds perhaps two trillion such galaxies.
6Mark asked how scientists can possibly measure such distances.
7They compare the brightness of stars whose true output is known.
8The guide explained that the universe is still expanding today.
9Distant galaxies are moving away faster than those nearby.
10Black holes form when massive stars collapse under their own gravity.
11Nothing, not even light, can escape from within their boundary.
12Yet matter spiralling into one shines with tremendous energy.
13The first image of a black hole required telescopes across the globe.
14Anna wondered whether life exists on planets around other stars.
15Thousands of such planets have already been confirmed so far.
16Some orbit within the zone where liquid water could exist.
17Researchers analyse their atmospheres for gases linked to life.
18No signal or sign of life has been detected yet anywhere.
19The silence makes every new discovery feel like an open question.
20They drove home slowly, still staring upward through the windows.