Interviews are the final part of any admission process to a PhD program. The possible invitation for an interview could take up to a month after the deadline for applying. Nowadays online interviews are becoming a thing very rapidly, mainly because of the pandemic situation and partly because applications for the position come from all over the world. And the institutes cannot always afford to fly out each candidate from the different parts of the world. Still, some institutes do that (or, used to do that, before the pandemic) -- they arrange a one-two days visit of the institutes for the candidate.
Usually, the selection committee informs candidates in advance about the procedure of the interview, however, it may not be the case always. This article is written to give the reader a general idea of the proceedings of such PhD interviews; again, these are all based on the experience of the author, so the actual process of the interview may be different.
It is a most general procedure to start a PhD interview with a brief presentation by the candidate on his/her research project(s). The interviewee is, in advance, asked to prepare a ~10-15 minute presentation on his/her research themes -- one can prepare slides on one’s Master’s thesis project or any other projects that are most relevant to the subject matter of the proposed doctoral project. Then there would be a brief question-answer session on the material just presented by the candidate. This tests how well the candidate has understood the subject matter. With this discussion, the first part of the interview session would be completed; this takes ~15-20 minutes in general.
How to continue in the second part is entirely dependent on the selection committee. They either choose to go by asking technical questions, or they may ask some non-technical questions as well. The former may include questions related to the research project or any general questions from the whole field of astronomy. Therefore it is advisable to read some basics of the field before appearing to the interview. The later course of the interview would include some work-related, but non-technical questions. These questions would be something like this:
Please note that this is not at all the whole list of questions that will be asked in your PhD interview. These are some of the questions that the author was asked during his PhD interview.
Finally, they would ask the candidate if s/he has some questions for the committee. Although it is completely okay to not ask any questions, it is good to ask something --- maybe more about the proposed research project. That would create a good impression in the mind of the interviewer.
The results for the interview is usually declared a week after the day of the interview.
All the best for your PhD application!