Telescope

Telescopes exist in The Sims, The Sims 2, and The Sims 3. They can be bought in buy mode. Using the telescope is Fun and increases your Logic.

Sims 1
The Horrorwitz 'Star-Track' Outdoor Telescope is a good way of increasing your Sim's Logic. However, if your Sim spends a long time looking through it (two or three points without taking a break), he or she will be abducted by aliens! A blue sphere will appear and your Sim will vanish for a few hours. When they return, their personalities will have turned upside down and they will think about aliens for quite a while afterward.

Sims 2
In The Sims 2, there are 2 telescopes, one cheap and one expensive. The Astrowonder (§550) and the Farstar e3 (§2100). But the price isn't the biggest difference - Sims using the Astrowonder won't ever be abducted, but with the Farstar it's possible. A male Sim who gets abducted will come back pregnant.

In The Sims 2: FreeTime, all of the telescope actions have a chance of alien abduction, but the Aspiration Benefit for Knowledge, Summon Aliens, allows your Sim to create a spotlight with a flashlight and the telescope, giving them a huge chance of abduction. In FreeTime, your Sims can also earn money discovering new celestial and astral bodies.

Using either telescope during daylight and accidentally (or "accidentally", with mods) looking at a Sim through the telescope will make those neighbors mad at you.

Being abducted is easier with boolprop testingcheatsenabled true - with this cheat active, shift click on the telescope of your choice, and add the command "Get Abducted" to the queue, your sim will be taken by aliens. However, this method isn't perfect as nearby sims will not get the memory of the abduction without using hacks.

Sims 3
The Sims 3 returns to only a single type of telescope, found under the Study->Hobbies section. In addition to increasing fun and logic, the telescope also allows a sim to Search The Galaxy in which case they may find and name a new celestial body, such as Stars, Moons, Planets, Comets, and Satellites.

Your sim may also see a meteorite fall to the ground, placing a map marker where your sim can go to retrieve it. This map marker eventually disappears, so you will have to be quick.

However, your sim does not seem to use it to spy on their neighbors, nor do aliens abduct the sim.