Earth is located within the Milky Way galaxy, specifically in one of its spiral arms known as the Orion Arm or Local Spur. The Milky Way is a barred spiral galaxy, and our solar system resides in the outskirts of this galaxy, roughly 26,000 to 28,000 light-years away from its center.
In terms of neighboring stars, Earth's closest stellar neighbor is Proxima Centauri, which is part of the Alpha Centauri star system. Proxima Centauri is located about 4.24 light-years away from us, making it the closest known star to our solar system.
When it comes to other galaxies, the nearest major galaxy to the Milky Way is the Andromeda Galaxy (M31). The Andromeda Galaxy is a spiral galaxy located approximately 2.537 million light-years away from us. It is visible as a faint, elongated smudge in the night sky under dark conditions.
As for Sirius, it is a binary star system consisting of Sirius A (the primary star) and Sirius B (a white dwarf). Sirius A is the brightest star visible from Earth and is located about 8.6 light-years away from us. It is part of the constellation Canis Major (the Greater Dog).
Overall, Earth's position within the vastness of outer space places us within the Milky Way galaxy, with neighboring stars such as Proxima Centauri and Sirius, and other galaxies like the Andromeda Galaxy existing at significant distances from our solar system.