First, let’s talk about what it means to “disturb” Earth’s orbit. Every object that hits Earth changes its orbit a little. Maybe you’re really interested in impacts that would change the planet’s orbit enough that
it would affect our everyday life — for example, by causing the year to be one day longer or shorter, or by causing winter to be noticeably warmer. Astronomy magazine subscribers can read the full answer for free. Just make sure you're registered with the website.