The closest approach is about 600,000 Km away. That’s more than twice the distance to the moon. At that distance, to be (just barely) visible to the naked eye, it would have to be about 170km across, which would put it among the largest asteroids in the solar system. In fact, 2024 PT5 is only about 11m across (~36ft). You would need quite a powerful telescope, indeed, to see an object that small at that distance.
The closest approach is about 600,000 Km away. That’s more than twice the distance to the moon. At that distance, to be (just barely) visible to the naked eye, it would have to be about 170km across, which would put it among the largest asteroids in the solar system. In fact, 2024 PT5 is only about 11m across (~36ft). You would need quite a powerful telescope, indeed, to see an object that small at that distance.