Imagine that we have an object with apparent magnitude $m_1$, later, we observe that the same object appears with an apparent magnitude $m_2 = m_1 + \alpha$, then what we can say about the absolute magnitude M? By the definition I believe we find that the absolute magnitude after the change in apparent magnitude will be $M_2 = M_1 + \alpha$. But this make sense? I mean, the absolute magnitude is that, absolute, what are your thoughts in this? What will be the change in the absolute magnitude after a change in the apparent magnitude?

  • $\begingroup$ Please edit the question to limit it to a specific problem with enough detail to identify an adequate answer. $\endgroup$
    – Community Bot
    Oct 1, 2022 at 9:11
  • $\begingroup$ By magnitude do you mean mass? Secondly, what is meant by absolute? $\endgroup$
    – Amit
    Feb 4 at 20:11
  • $\begingroup$ @Amit these are all standard terms. No explanation is required. $\endgroup$
    – ProfRob
    Feb 4 at 23:05
  • $\begingroup$ @ProfRob I apologize, I wasn't aware of this jargon. Learned something new :) $\endgroup$
    – Amit
    Feb 4 at 23:20

1 Answer 1


The absolute and apparent magnitude are simply related by the distance to the source.

If the distance is fixed and the apparent magnitude changes, then the absolute magnitude must have changed by the same amount.

The absolute magnitude is not called that because it can never change - there are lots of examples of variable stars. It merely refers to the fact that it is the apparent magnitude if the object were at a defined distance of 10 pc.


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