First, don't worry about advice from astronomers. By the time you get your PhD and are looking for a job, the climate will be completely different and no one can tell you for certain what things will be like in 10 years. I would say, follow your heart and your mind. Make certain you have picked up lots of skills...computer programming in C or C++ seems to be the IN thing these days...and just keep being enthusiastic. When I was an undergraduate, the Apollo Program had been shut down and things looked bleak. In planetary astronomy, there will be lots happening because of all of the missions being planned and built. Also, Baby Boomer astronomers will be retiring so in the next 10 years there will be lots of opportunities for the next generation.
You need to get busy mastering math and physics and chemistry, and some geophysics will be very helpful too. Try to excel in these subjects and get lots of B+ and A grades. But also keep your eye on the developments in the field and learn the lingo and issues.