In 1990, Carl Sagan requested NASA to turn Voyager 1 around to capture an image of Earth from 4 billion miles away. Earth is the dot halfway down the line on the right.
"We succeeded in taking that picture, and, if you look at it, you see a dot. That's here. That's home. That's us. On it, everyone you ever heard of, every human being who ever lived, lived out their lives. The aggregate of all our joys and sufferings, thousands of confident religions, ideologies and economic doctrines, every hunter and forager, every hero and coward, every creator and destroyer of civilizations, every king and peasant, every young couple in love, every hopeful child, every mother and father, every inventor and explorer, every teacher of morals, every corrupt politician, every superstar, every supreme leader, every saint and sinner in the history of our species, lived there on a mote of dust, suspended in a sunbeam. The earth is a very small stage in a vast cosmic arena. Think of the rivers of blood spilled by all those generals and emperors so that in glory and in triumph they could become the momentary masters of a fraction of a dot. Think of the endless cruelties visited by the inhabitants of one corner of the dot on scarcely distinguishable inhabitants of some other corner of the dot. How frequent their misunderstandings, how eager they are to kill one another, how fervent their hatreds. Our posturings, our imagined self-importance, the delusion that we have some privileged position in the universe, are challenged by this point of pale light. Our planet is a lonely speck in the great enveloping cosmic dark. In our obscurity -- in all this vastness -- there is no hint that help will come from elsewhere to save us from ourselves. It is up to us. It's been said that astronomy is a humbling, and I might add, a character building experience. To my mind, there is perhaps no better demonstration of the folly of human conceits than this distant image of our tiny world. To me, it underscores our responsibility to deal more kindly and compassionately with one another and to preserve and cherish that pale blue dot, the only home we've ever known."
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But if (as might be the case), we are the only living things in the galaxy capable of thinking thoughts like these, we might regain some measure of pride.
As Fermi famously asked, "If the universe is teeming with intelligent aliens, where are they?"
"There are billions of stars in the Milky Way similar to the Sun. With high probability, some of these stars have Earth-like planets in a circumstellar habitable zone.
Many of these stars, and hence their planets, are much older than the Sun. If Earth-like planets are typical, some may have developed intelligent life long ago.
Some of these civilizations may have developed interstellar travel, a step that humans are investigating.
Even at the slow pace of envisioned interstellar travel, the Milky Way galaxy could be completely traversed in a few million years.
Since many of the Sun-like stars are billions of years older than the Sun, the Earth should have already been visited by extraterrestrial civilizations, or at least their probes.
However, there is no convincing evidence that this has happened."
We have satellites around the moon and all the major planets of the Solar System.
Don't you suppose the aliens would have left some satellites circling the Earth to keep tabs on a rare planet that they found harboring intelligent life? What would we do if we found a planet with intelligent life? Just let the primitives carve a few stone artifacts about our visit?
@Thinkerbell Faster than light travel is theoretically impossible (and may in fact be impossible, Alcubierre drives notwithstanding). Maybe aliens don't want to embark on journeys of thousands of years over many generations when they could explore the universe as we're doing, with robotic probes and space telescopes.
