If an Earth-sized planet grazed over the surface of Earth by a couple of hundred feet and never actually touched, how badly would that disrupt my day?

25053 MPH

That’s all you need to know about this scenario.

In order to avoid being captured by earth’s gravity, you need to travel about 25,000 MPH at sea level. This means that your “graze over the surface” planet would be traveling at 25,000 MPH. Much less and it will simply hit the earth as it’s captured by earth’s gravity.

If a SMALL object comes into the atmosphere at 25.000 MPH, bad things happen.

This is a round from a rail gun travelling at about 5,000 MPH. Notice that it’s moving so fast that the air is simply igniting in it’s wake. Multiply that by 10. Then make the projectile the size of a planet.

Everyone dies.

Edit: Thanks for all the “we would actually die faster than that” answers. This isn’t a realistic scenario so I didn’t think actual math was required.

Yes, we would all die before the planet got that close.