What is this? 020

cm is centimeters, km is kilometers

A log scale. Each increment goes up by a factor of 10.

A magnitude is a vague term; however, it is often used to refer to the power of 10. So, for instance, 1200 = 1.2 x 10³ and 2600 = 2.6 x 10³ would both be on the same order of magnitude (referring to the 3).

Sometimes, “the same order of magnitude” can refer to numbers that round to the same nearest power of 10. For instance, 900 and 1100 would be on the same order of magnitude.

This is a useful concept when you are dealing with many orders of magnitude, to give you a rough estimate of what scale you are talking about. For instance, the mass of a proton and the mass of a neutron are on the same order of magnitude, but the mass of a proton and the mass of an electron are on very different orders of magnitude.

10 cm

It’s important to understand that none of these are exact and some are not even that close, but they are on the same order of magnitude.

An asteroid is orbiting the sun.

A meteorite is a meteor that survived to hit the ground.

The lowest level of biological classification.

The second highest level of biological classification, just below Kingdom.

The biosphere is the region that includes all life on Earth.

There are 7: Asia, Europe, Africa, North America, South America, Australia, and Antarctica

This refers to the theory that the Earth’s moon was formed when the Earth was struck by an asteroid in this size range, implying that if the Earth were struck by a similar asteroid again, a new moon would form.

The diameter of the Earth is about 13,000 km. If the Earth were about to be hit by an asteroid with a diameter larger than this, then it would be equivalent to the larger object being hit by the Earth instead.

xkcd