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 a Sim's Logic. In The Sims 4, the telescope is replaced by a backyard observatory.

The Sims
The Horrorwitz "Star-Track" Backyard Telescope is a good way of increasing a Sim's Logic skill. However, a Sim who spends a long time looking through it (two or three points without taking a break), may be abducted by aliens. A blue sphere will appear, and the Sim will vanish for a few hours. When the Sim returns, their personality will have been reversed, and they will think about aliens for quite a while afterward.

The Sims 2
In The Sims 2, there are two telescopes, the Astrowonder (§550) and the Farstar e3 (§2100). The price isn't the biggest difference - Sims using the Astrowonder won't ever be abducted (unless cheats or hacks are used to force an abduction), but with the Farstar it's possible. If an adult male Sim who is more than 5 days away from becoming an elder gets abducted, he will come back pregnant.

Children can use the telescopes, but will appear to levitate while doing so, as the booster stool they normally use will not appear.

In The Sims 2, a telescope can be used indoors, so long as it is pointed out a window. The window can be single-tile or multi-tile, but the left side of the telescope has to be facing a window for it to be usable. This can be seen in the Tinker family's house in Bluewater Village, which has a Farstar e3 pointed out a second-floor window.

In The Sims 2: FreeTime, using the telescope builds enthusiasm for the Science hobby. All of the telescope actions have a chance of alien abduction, but the Aspiration Benefit for Knowledge, Summon Aliens, allows a Sim to create a spotlight with a flashlight and the telescope, giving them a huge chance of abduction. This can be used with either telescope, but will not be available if the telescope is indoors. It is also unavailable on the telescope at Aspirational Laboratories. It also appears to be different from other telescope actions, as it does not appear to build the Logic skill. In FreeTime, Sims can also earn money by 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 the Sim using the telescope. Even so, Sims may do it autonomously.

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, in order to have the Sim taken by aliens. However, this method isn't perfect as nearby Sims will not get the memory of the abduction without using hacks. This method does not work after The Sims 2: FreeTime is installed.

Practically, the first Sim instance in the neighborhood data, as seen in SimPE (not necessarily the first Sim created), is always going to shove anyone spying on them. But whenever the player is playing with the family/household of that Sim, the first of the secondary family will shove the Sim instead. The following table will show all neighborhoods, and the Sims that will shove any spying neighbor:

Astrowonder Telescope
Fun: 4

+Logic

Farstar e3 Telescope
Fun: 10

Environment: 2

+Logic

The Sims 3
The Sims 3 base game returns to having a single type of telescope, found under the Study-&gt;Hobbies section. The Outdoor Living stuff pack adds another type.

In addition to increasing fun and logic, a 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.

The Sim may also see a meteorite fall to the ground. This will place a map marker where the Sim can go to retrieve it. This map marker eventually disappears, so the player will have to be quick.

Sims can get abducted when they search the galaxy at night.

However, Sims do not seem to use telescopes to spy on their neighbors.

Astral Playground Telescope
Fun: 2

Environment: 3

Morrigan's Star Gazer
Fun: 2

Environment: 3

Perseus Astronomical Telescope by Arasika Industries
Fun: 2

Environment: 3