710 is "okay" for astronomy programs. That is, it is not going to be one of the top scores, but it will not be low enough to raise any concerns either. See also: http://mahalonottrash.blogspot.com/2014 ... fails.html
(shows distribution of Caltech Astro admitted students' Physics GRE scores). 710 is right in the middle. However, if you are on a physics/theory slant, then you are likely competing with people who have higher PGRE scores.
Even so, I was answering your post not from the framework of "what can be improved" but instead, "is there anything with your GRE score that can hurt you, even with all the other great stuff about you". And the answer to that is your GRE V score.
A 143 on the verbal combined with a 3.5 on the AW is a concern in my opinion. 143 is less than 20th percentile. I think if you had a higher GRE V score, then 3.5/6 on AW is not as big of a concern.
I think you should at least get to 50th percentile on your GRE V score.