1. **Watch Alien Movies and TV Shows**: Marathon some of the best alien-themed films and series like “E.T.”, “Alien”, “Independence Day”, “Men in Black”, “The X-Files”, or “Stranger Things”.

2. **UFO Sightings and Extraterrestrial Theories**: Dive into documentaries or YouTube videos about famous UFO sightings, Area 51, and various extraterrestrial theories. Shows like “Ancient Aliens” can be fascinating to watch.

3. **Alien-Themed Snacks and Drinks**: Make some fun, alien-themed snacks and drinks. You can create green smoothies, alien cupcakes, or cookies shaped like UFOs and aliens.

4. **Alien Costume Party**: Host a costume party where everyone dresses up as their favorite alien or sci-fi character. You could even have a contest for the best costume.

5. **Star Gazing**: Take some time to stargaze and ponder the vastness of the universe. If you have a telescope, use it to get a closer look at the stars and planets.

6. **Read Alien Books**: Pick up some sci-fi books that explore the theme of aliens and extraterrestrial life. Authors like H.G. Wells, Arthur C. Clarke, and Isaac Asimov have written some classics in this genre.

7. **Alien Crafts and Activities**: Get creative with some alien-themed crafts. You can make alien masks, build your own UFOs out of household materials, or paint pictures of what you think aliens might look like.

8. **Virtual Reality Space Adventures**: If you have a VR headset, explore space-themed VR games and experiences that can make you feel like you’re traveling to distant planets.

Enjoy your celebration of Alien Day and the mysteries of the unknown!