It's a "mini-me" version of its neighbouring supermassive "cousin" - shedding light on how it formed.
Given that the sun is over a hundred times the size of our little planet, that means this black hole is an absolutely ridiculous size.
While astronomers were aware of their existence - until now, none had ever actually been identified.
Lying about 25,000 light years from Earth it could help answer one of the really big questions - how did the Milky Way evolve?
In a study published in Nature Astronomy, scientists led by Tomoharu Oka from Keio University, Japan, announced a new candidate for an IMBH.
"That growth should happen in part by mergers with other black holes and in part by accretion of material from the part of the galaxy that surrounds the black hole". Instead, the scientists suggest it is the former core of a dwarf galaxy that has been subsumed into the Milky Way, stripped of its stars, and is destined to one day fall into Sgr A*.
It is widely accepted that extremely large galaxies contain at their centres supermassive black holes (SMBHs) with masses between a million and several billion times that of the sun - but how these form is unclear. "Thus we are increasing the number of them by the new technique".
"One possible scenario is IMBHs - which are formed by the runaway coalescence of stars in young compact star clusters - merge at the centre of a galaxy to form a supermassive black hole, " said Prof Oka. They also don't have the extreme conditions required to become a supermassive black hole.
But if this is the case, then how did the black hole form, and how did it get to the near-center of the galaxy?
But such black holes had not previously been reliably detected and their existence has been fiercely debated among the astronomical community.
The most likely cause, according to computer models, was a black hole no more than 1.4 trillion kilometres across. The largest, supermassive black holes, lurk at the center of galaxies, while small black holes result from the collapse of huge stars.
"Based on the careful analysis of gas kinematics, we concluded a compact object with a mass of about 100,000 solar masses is lurking in this cloud", Prof Oka added. Additionally, the lack of any counterparts at other wavelengths at all suggests that it's an inactive IMBH that isn't now consuming any more matter or growing.
Researches have predicted that about 100 million holes should exist in the Milky way Galaxy out of which only 60 has been identified till now.
Artistic representation of a black hole. The term itself did not come into use until 1967, and it was just 46 years ago that the first one was identified.