This is a fun thought experiment! Here's how to figure out the relative size:

The Scale:

* Earth: Let's say the ballpoint pen tip is about 1 cm in diameter.

* Sun: The sun is about 109 times wider than Earth.

Calculation:

* If the Earth is 1 cm, the sun would be 109 cm wide.

Real-World Comparison:

* A 109 cm diameter sphere is about the size of a large beach ball.

So, if the Earth was the size of a ballpoint pen tip, the sun would be about the size of a large beach ball.