Arcturus (Alpha Boötis) is the brightest star in the constellation Boötes, and the third brightest star in the night sky, with a visual magnitude of ?0.05, after Sirius and Canopus. It is the second brightest star visible from northern latitudes and the brightest star in the northern celestial hemisphere. The star is in the Local Interstellar Cloud. An easy way to find Arcturus is to follow the arc of the handle of the Big Dipper. By continuing in this path, one can find Spica (? Virginis) as well — hence the maxim, "Arc to Arcturus, then speed on to Spica.". It is located 36.7 light years from Sol.

In Star Trek, the Arcturians were a humanoid species that had been encountered by the Federation by latter half fof the 23rd century. By the 2270s, they were serving in Starfleet. An Arcturian Starfleet officer was speaking with two Rhaandarite at the air tram station in San Francisco on stardate 7410.2. (Star Trek: The Motion Picture) The three were seen on the lower platform in the background when James T. Kirk and Sonak parted ways at the top of the escalator.

Having an appreciation for Shakespeare, a popular version of Macbeth was re-envisioned by the Arcturians. Sponsored by the Galactic Cultural Exchange Project this rendition was notably performed by the Karidian Company of Players, a touring theatrical troupe headed by Anton Karidian, in 2266. (TOS: "The Conscience of the King")

A popular beverage on Arcturus IV was the Arcturian fizz. (TNG: "Ménage à Troi")

In reality, Arcturus is a type K1.5 IIIpe red giant star — the letters "pe" stand for "peculiar emission," which indicates that the spectrum of light given off by the star is unusual and full of emission lines. This is not too uncommon in red giants, but Arcturus has a particularly strong case of the phenomenon. It is at least 110 times more luminous than the Sun, but this underestimates its strength as much of the "light" it gives off is in the infrared; total power output is about 180 times that of the Sun. The lower output in visible light is due to a lower efficacy as the star has a lower surface temperature than the Sun.

In astronomy, the Arcturus Stream is a stellar stream, including the nearby bright star Arcturus which share similar proper motion. This stream is not in the plane of the Milky Way galaxy and is likely the remnants of an ancient dwarf satellite galaxy, long since disrupted and assimilated into the Milky Way. It consists of old stars deficient in heavy elements.