To prevent users from changing the name of the planet, you can develop a Item Updating event receiver.
This event occurs before the data is saved to the Share Point list.
To check if the name of the planet is changed, you can compare the Title column before the changes with the Title of the changed item.
The changed values can be retrieved from the After Properties of the incoming properties argument.
The second time they fire it is in response to the document being checked in.If you find yourself in this situation, then you’ll have to solve the problem in code.Fortunately, there is a relatively simple way to check whether the Item Updating and Item Updated events are firing in response to a check-in outlined in Knowledgebase Article 939307.Instead of writing more paragraphs I can use tabular to explain, I think this will be easy to understand.Each event method has a SPItem Event Properties parameter named properties.