Some asteroids have Japanese names, like Totoro and Hokusai. How do they get their names? First, a new asteroid gets a number. Then the person who found it can suggest a name. A group of experts checks the name. There are rules.

For example, a name must be 16 letters or less, and it should not be the name of a pet. Many Japanese names come from Japanese amateur astronomers.

When a new asteroid is found, it first gets a temporary code. After its orbit is well known, it receives an official number, and then its discoverer has ten years to propose a name. The proposal must include a short English explanation, and a working group of the International Astronomical Union reviews it. The rules are strict.

Names can have no more than 16 letters, numbers cannot be used, and pet names and product names should be avoided. Discoverers also cannot name an asteroid after themselves. Many asteroids have Japanese names, such as Totoro and Yukawa, partly because Japanese amateur astronomers found large numbers of asteroids in the 1980s and 1990s.

Asteroids pass through several stages before they can be named. A newly found object receives a provisional designation such as "1994 YQ1," and once repeated observations pin down its orbit, the Minor Planet Center assigns it a permanent number. Under the rules of the International Astronomical Union's working group on small-body nomenclature, the discoverer then has ten years to propose a name, accompanied by an English citation of up to 360 characters.

A name becomes official only when it appears in the group's bulletin. The criteria are strict: names are limited to 16 characters, may not contain numbers and should not honor pets or promote commercial products, while names of political or military figures and events must wait 100 years. Discoverers are also barred from using their own surnames.

Japanese-related names are common, largely because Japanese amateur astronomers ranked among the world's most productive discoverers in the 1980s and 1990s; (10160) Totoro, for instance, was found in Gunma in 1994. But nationality does not determine naming. Hokusai was discovered in the United States in 1960, and both Itokawa and Ryugu were found by an American survey before receiving Japanese names.