Towards the end of Avengers: Infinity war, after
Thor managed to re-light the forge and create Stormbreaker
Thor, Rocket, and Groot
use the Bifrost ability of the newly forged weapon to go to Wakanda.
They land exactly in the middle of where they're needed. I understand Thor knew their next stop should be Earth, but how could he possibly know to take them directly to
Wakanda?
After the events of Ragnarok, Thor is now the All-Father. He is capable of many feats that have not been shown on screen yet, which Thor begins to unlock when he wields Stormbreaker(a kings weapon). This is what allows him to open the bifrost, and it is certainly within the realm of possibilities that the awakening and development of his new powers includes some form of Odinsight, which the All-Fathers past have used to watch over the 9 realms. He could have used the Odinsight to see the events unfolding on earth and decide where to go.
The traditional presentation of Odin (the traditional All-Father) is "all-seeing, all-knowing and aware of the past and the future", after his three sacrifices, the powers and knowledge of the All-Father are too immense to list, though an overview was given in another question. More on Odin available here and here
In the Marvel universe, Thor has taken up the mantle and powers of the All-Father in several storylines and alternate universes, though he is not often referred to by the full title. In the comics his aliases include: Thor the Father, All Black the All Father, and AllFather Thor. He even holds his own in a solo showdown with Galactus. He's also referred to as old-king thor, and the Odinforce has been renamed the Thorforce, as it is the force of the All-Father.
Can't they see (hear) through the bifrost, or it has its own sensing abilities. Heimdell was not operating the bifrost in ragnarok, but the remote call from Thor was still heard in the bifrost room.
They can probably open the portal to "Earth", and from that determine the location of the fight, or possibly of his avenger friends, or even vision's stone and the precisely direct (except Heimdell who had "the sight").
When they use the bifrost they always appear at precisely the correct place, how could they know where Jane is when he pops by to see her in the dark world, they probably see earth then can pinpoint to specific places after that.
Or like Heimdell, maybe having control of the bifrost gives you "the sight" to see where you want to go before you go there.
But I'm not a bifrost engineer, so who knows, maybe it's just good screenplay writing where something important happens at precisely the correct time.
It's not explained and/or it happened off screen, but here is an idea:
In the post-credits scene, we see Maria Hill and Nick Fury talking about an energy signature coming from Wakanda that is ten times higher/stronger than the signature from New York in Avengers 1.
Now, Thor was with Rocket, let's assume Rocket has devices that can track these kind of energy signatures similar or better than Nick Fury's.
Rocket traced these signatures and found the greatest one from Wakanda and this is the way Thor knew he had to go to Wakanda.
Either he didn't go there directly and they "hopped" there after finding out, when they arrived on Earth.
OR....Thor's a hyper-advanced being. It could be that the Stormbreaker has some sort of homing ability to the Tesseract stone of power and that's how Thor knew exactly where to go.
Here’s how I could see this working.
The Avengers have communication devices. Geolocation would be a reasonable feature to expect of a Tony Stark developed communicator.
Recall how “Foster's cell phone gains reception and they venture deeper into the cave” in Thor: The Dark World? So we know cell communication via a portal is feasible.
Thor opens a portal using his Axe, Stormbreaker... He pinpoints the location via his Avenger communication device, then adjusts the portal destination before walking through.
It's never established. Many answers were already given, but there's one possibility so far unmentioned:
Thanos' ships were hovering over Wakanda.
It doesn't even need to be precise. Given that the ships are vaguely hovering near Wakanda, it's a reasonable guess for Thor to assume that the others have sought refuge in Wakanda.
My assumption was that like with Heimdall, he has some power to see across the universe at least while wielding Stormbreaker. He would have been able to view Earth that way and see where to send his group.
