You could use a pair of calipers. Alternatively, measure its circumference using a piece of string and divide the measure by pi.
Internal diameter.
The radius of a circle is half the diameter.
with a big tape measure
If you know the radius, double that to get diameter. If you have neither radius or diameter, then measure around the outside.
Not normally
Mercury's diameter from pole to pole is approximately 4,880 kilometers.
The exact diameter of the geographic north pole (like the south pole) is in theory zero.
For the width, measure the length of the track or pole and add an inch for overlap in the middle. The height should be measured from the top of the track or the small metal ring for a pole.
The diameter of the Moon is approximately 3,474.8 kilometers.
To measure a curtain ring, you would typically measure the diameter of the inner circle on the ring. This measurement will help you determine the size of the curtain rod or pole that the ring will fit onto.
The polar diameter of a celestial body, such as a planet or star, refers to the distance between its two poles, which are the points on its axis of rotation. This measurement is typically shorter than the equatorial diameter, which is the distance between two points on the body's equator. The polar diameter is an important parameter in understanding the shape and rotational characteristics of celestial bodies.
Jupiter has about 1/10 the diameter of the Sun. Note that due to its fast rotation, there is a fairly large difference in the diameter, depending on whether you measure from pole to pole, or from equator to equator. Jupiter also has about 1/1000 the volume of the Sun, and 1/1000 of the Sun's mass.
Internal diameter.
The Earth has a diameter of about 12,742 kilometers, which is equivalent to 12.742 million meters.
The Earth's diameter from the North Pole to the South Pole is approximately 12,714 kilometers.
A 'metal pole' could be made out of so many different types of metal, but most likely the metals you are looking for are Iron, Steel or a Chrome-plated pole.
A caliper is a common tool used to measure the diameter of a metal rod. It consists of two hinged legs with a scale and a mechanism to precisely adjust the distance between the tips. By placing the rod between the tips and closing the caliper, the diameter can be accurately read off the scale. Calipers come in various types such as digital, dial, and vernier, each offering different levels of precision.