What would happen if we discovered a planet with alien life technologically 100 years behind us?

The furthest boundary of our Solar System extends up to 100,000 AU, i.e., 100,000 times the distance between Earth and the Sun or 1.87 light-years away.

Interesting to note that Pluto averages around 40 AU from the Sun, and we never had a better-looking picture of it until New Horizons met it in the middle of 2015.

And life could linger in many forms and places depending upon how it evolved. For simplicity let us assume that such a civilization evolved inside a volcanic Planet X (maybe a dwarf) with warm oceans but protected by very thick ice shields from the outside.

Such a planet would spend millions and millions of years on the fringes of the solar system; frigid, desolate from the outside but completely self sufficient internally due to active thermal activities.

artist’s concept of the cryobot and its deployed ‘hydrobot’ submersible. Right: Europa Lander Mission concept, Courtesy : NASA 2005

That is enough to support evolution of life similar to Earth, but completely inside the thick ice shield. So they have been evolving like us for millions and millions of years.

Now to comply with the original question let me assume two things – Planet X is 100 years behind us in technology, very easy to assume.
They are as close as the Moon, not easy to imagine scientifically. So let’s twist the story.

Imagine some hundred thousand years ago Planet X was nudged from its orbit by a gravitational interaction from a nearby neighboring object, resulting in an inward spiral towards the Sun.

And just a couple of years ago an amateur astronomer on Earth found it at a distance as near as Jupiter; still circling the Sun in an ever decreasing radial distance.

Planet X’s civilization being just 100 years behind us in technology, they would be very intelligent; in possession of tools and technology with which we fought the First World War.

Radio communication, Submarines (instead of air planes, since they are aquatic life form), Electricity, Transportation, Metallurgy, advanced weapons etc would be very common; basically everything that the First Industrial Revolution gave us would be in their hands.

With both of us making contact with each other at a distance close to where Jupiter is, they are in real and immediate danger of perishing with Planet X’s ice shield starting to crack with the ever growing warmth of the Sun as they make their approach to it.

What could we do?

Let’s suppose we calculate that they have around 50 years before they dip below the radial distance of 1 AU after which Planet X’s ice shield will crack wide open, leaving them exposed to the Sun.

Cutaway diagram of Europa’s interior. Artwork credit: NASA & Michael Carroll

Despite how hopeless we see ourselves as a Mankind we had agreed to leave many places on Earth beyond exploration and exploitation. And this finding will define how we will act upon finding a civilization similar to us.

Since Planet X’s civilization is advanced enough our job will not be very difficult, all we need to do is transfer our knowledge and technology to them. And all they have to do is quickly figure out how to save their planet with a joint venture between Planet Earth and X.

There are many possible ways of stopping this spiral to death and I would not go there, but to name a few is to use the same gravitational nudge that put them towards their journey to the Sun. Maybe use the gravity of Jupiter or Mars to correct the orbit. Or using blast jets on their surface to settle down in a new orbit somewhere between the Asteroid belt and Jupiter.

Eventually, they will survive and we will end up having a long term friendship with another intelligent life form; the only one we ever came to know about.

In the end this experience will completely redefine how we see life and more importantly an intelligent life!