Flaming Sphere question

[GerryWright]

At a gaming session last week we had a disagreement about how close to a flaming sphere you have to be to take damage. Some said that ending your turn within 5 feet meant being within 5 feet of its center point. In other words, you have to be in contact with it to take damage. Others said that being within 5 feet meant within 5 feet of its edge. this would mean you could be 10 feet from the center, not in contact with the sphere, and still take damage. Which is the correct interpretation?

[Zacchaeus]

The sphere is 5ft in diameter. So if you are in a square adjacent to where the sphere is then you are within 5ft of it and take damage. If you are 10ft away you can't be adjacent to it - even if you interpret the range as starting from the edge of the sphere.