I would say that it matters not-at-all whether your name is Aardvark or Zygote. Astrophysicists are not stupid, we can see when a large author list has been alphabetised. If anything I would say it is a disadvantage, since a casual glance at an author list might lead someone to think you were the lead author of any paper, even one with just two authors, simply because of your surname.
In practice, the tiny minority of author lists are alphabetised in Astrophysics papers. Off the top of my head I can think of the gravitational wave papers by Abbott et al. and the MACHO papers by Alcock et al. Most many-author papers have a nucleus of authors at the start of the work and then a longer list of names, possibly in alphabetical order, of people who contributed to the overall project or mission. Even these papers are a (growing) minority and it is still true that the majority of Astrophysics papers have a relatively small author list ordered by contribution.
Finally, I will add another personal opinion. The presence of someone's name on many long-author list papers does not necessarily impress me unless they have lead some of them. It is more impressive for a young scientist to have forged their own path and perhaps written a few lead-authored papers with small author lists or even a sole author paper. Unfortunately, much "big science" does involve big consortia and though it can be exciting for an early-career scientist to be part of such an enterprise, it can be much harder to make your mark outside of that consortium.
EDIT: As a brief, empirical check on my answer, I looked at arXiv for 22nd November 2016. There were 66 new astrophysics papers listed. Of these, 29 were written by three or fewer authors. Only five were written by $>10$ authors and only one paper, from the Pierre Auger collaboration, appeared to have an alphabetised author list. Try hard not to laugh - the paper is by Aab, A. et al. Good luck in your efforts to beat that.