Here are some factors that complicate the answer:
* Defining "major": What criteria are we using? Number of speakers? Geographical distribution? Political influence?
* Dialects vs. Languages: Is a dialect of a language considered a separate language? This can be a very complex question, with no clear answer.
* Language families: Do we count languages within the same family as separate, or as branches of a larger linguistic group?
* Continuously evolving language: Languages change constantly, making it difficult to draw firm lines between "major" and "minor" languages.
However, here are some potential approaches to the question:
* The Ethnologue: This database lists around 7,100 languages worldwide. While not all of these are "major," it gives a sense of the vast diversity.
* Top 10 most spoken languages: Based on the number of speakers, the top 10 languages are Mandarin Chinese, English, Hindi, Spanish, Arabic, Bengali, Portuguese, Russian, Japanese, and Punjabi.
* Official languages: Many countries have official languages, which often have a significant number of speakers within that nation.
Ultimately, the answer to how many "major" languages are spoken on Earth depends on how you define "major." The important thing to remember is that language diversity is a precious part of our global culture.