Notes

Extraterrestrial Life Exists
There are many arguments for, and against the existence of extraterrestrial life. The argument for the existence of extraterrestrial life can be greatly supported by the water on Mars, possible communication, and the extreme likeliness of alien life.
First, the argument for the existence of extraterrestrial life can be greatly supported by water on Mars. There are geological formations that go very far to prove the fact that mars may have had, and may still have water. All living things require water to survive, and if there are planets with water in our solar system, there may be many others outside of our solar system which also have water. A view under Mars' surface with a radar shows that there is a great volume of water under its surface. The unquestionable view from the radar instrument on NASA's Mars Reconnaissance Orbiter seems to give a compelling argument that immensely supports the existence of extraterrestrial life.
Another argument for the existence of alien life is the fact of possible communication with extraterrestrial life. The Wow! Signal is one of the proofs of possible communication with alien life. The Wow! Signal, as is stated by Jesse Emspak, was thought to be a comet, but was proven wrong: “To see if a signal could have come from comets, Paris first used a radio telescope to look at the sky in the region of the Wow! Signal. (...) The comet passed near, but not exactly, where the Wow! signal was — about 2 degrees north of the Wow! signal location. (12-13)” If the mysterious signal was not originated from a comet, the likelihood that the signal was from an extraterrestrial source increases tenfold.
Finally, another argument for the existence of alien life is the extreme likeliness of the existence of it. There are approximately 1,000,000,000,000,000,000,000,000 stars. Most of those stars probably have planets. This is a lot of planets in which aliens could possibly reside in. According to Marc Kaufman, “While no clear signs of life have ever been detected, the possibility of extraterrestrial biology – the scientific logic that supports it – has grown increasingly plausible. (3)” He evidently states that it is highly likely that extraterrestrial life exists. Also, according to NASA, “A recent statistical estimate places, on average, at least one planet around every star in the galaxy. That means there's something on the order of a trillion planets in our galaxy alone, many of them in Earth’s size range. (5)” Also according to NASA,
“Right now we know, for the first time, that small planets are very common,” said Sara Seager, a professor at the Massachusetts Institute of Technology and an exoplanet research pioneer. “It’s phenomenal. We had no way to know that before Kepler. We’ll just say, colloquially: They’re everywhere.” (5-6)” Yet another quote from NASA states that many exoplanets with possibilities of alien life have been found: “So how is the search going? In just over 20 years of exploration, ground and space-based observations have turned up more than 3,200 confirmed exoplanets in the few slices of our galaxy we’ve been able to search. Add unconfirmed planetary candidates and the number jumps to more than 5,600. (10)” This unquestionably accurate information leads to the realization that extraterrestrial life is plausible. The odds of there being even just a single planet in the universe that has any extraterrestrial life are very high, and there is almost no doubt that alien life exists somewhere in the universe. Since there are approximately septillion stars in the universe, the probability of the nonexistence of aliens is no more than one in septillion. This is similar to the odds of rolling a die, and the die landing on one thirty-one times. This information makes it almost undeniable the fact that alien life does exist. Also, a star called the tabby star has had a dimming phase before. The star seems to dim in brightness up to 20% and the reason for that does not pertain to comets, meteors, or planets. This could potentially be a Dyson swarm invented by aliens or something else we humans haven’t seen before. Scientists believe that this object could be at the right distance for life to exist on the object: “the timing of the present dip suggests that whatever this material is, it is situated at just the right distance from the star to be in the “habitable zone,” where we believe that life like ours could develop as it has on Earth. (Gerry Harp, 2)” These facts greatly aid the argument that extraterrestrial life may exist in the universe.
In conclusion, the existence of extraterrestrial life can be immeasurably backed by the water on Mars, possible communication with aliens, and the extreme likeliness of the existence of alien life. The existence of extraterrestrial life in the universe is highly unlikely, and we must embrace the hard fact that aliens may invade our planet or the fact that aliens and humans will one day discover each other, and cooperate.