In H.G. Wells' "War of the Worlds", the invading aliens are Martians, who come to Earth in cylindrical spaceships and wreak havoc with their advanced technology.

Carl Sagan was a renowned astronomer and astrophysicist who dedicated much of his career to studying the possibility of extraterrestrial life and promoting scientific exploration of the cosmos.

E.T. is the name of the lovable alien in the movie "E.T. the Extra-Terrestrial", who forms a special bond with Elliott and embarks on an adventure to return home.

UFO stands for "Unidentified Flying Object" and refers to any object or phenomenon in the sky that cannot be immediately identified or explained.

NASA (National Aeronautics and Space Administration) is the space agency of the United States and is responsible for various space exploration missions, including the search for extraterrestrial life.

The Arecibo Observatory was a large radio telescope located in Puerto Rico that was used for various scientific research, including the search for extraterrestrial signals.

Fox Mulder and Dana Scully are the two FBI agents in "The X-Files" who investigate paranormal and extraterrestrial phenomena, often encountering strange and unexplained cases.

Robin Hanson, an economist and futurist, proposed the idea of a "Great Filter" that prevents advanced civilizations from reaching a certain level of technological development, suggesting that there may be challenges or obstacles that limit their progress.

The Drake Equation is a formula that attempts to estimate the number of advanced civilizations in the Milky Way galaxy by considering factors such as the rate of star formation, the fraction of stars with planets, and the probability of life arising on those planets.

In the movie "Arrival", the Heptapods are the alien species that communicate with humans using a complex written language that resembles circular symbols.

John A. Wheeler, a renowned physicist and cosmologist, proposed the idea of a "cosmic zoo" hypothesis, suggesting that advanced civilizations may be observing and studying us, similar to how humans observe animals in a zoo.

Project SETI is a long-standing initiative dedicated to the search for extraterrestrial intelligence through the detection of radio signals from advanced civilizations.

Carl Sagan, a renowned astronomer and author, wrote the book "Contact", which explores the possibility of communication with extraterrestrial civilizations and the implications of such contact.

Voyager 1 is a space probe launched in 1977 that has explored the outer planets of our solar system, including Jupiter, Saturn, Uranus, and Neptune, and is now traveling through interstellar space.

The Doctor is the protagonist of the TV series "Doctor Who", a time-traveling alien who explores the universe in a spaceship called the TARDIS, encountering various adventures and challenges.