Once again, George is neglecting his duties; talking to Sammy rather than tending to that overgrown garden. When Lynne emerges it's as though she is coming out of a forest. From all these times of seeing their garden, we may have to now accept that this is the way they like it.
George's comment leads to two schools of thought. The first is that the astronomy like Lynne's body, heavenly meaning very nice. This is no way to run an astronomy club. All the men will be ogling Lynne and leave her to make all the decisions. If they're not careful, she'll blow their government grant on perfume and pants. The other explanation is that the astronomy club would never misappropriate the the term heavenly body. This means that they think that Lynne is the size of a small planet. The only reason that the astronomy club want Lynne to be their chairperson is so they can laugh at her. That's just cruel.
If they had said that Lynne had 'heavenly bodies' then that would be correct on both counts. This astronomy club is shambles. However if Sammy finds out they have free punch at the AGM, he'll join in a flash.