It depends on the kind of astrophotography you're doing

The other comment covers the zoom aspect of it

Whereas for landscape astrophotography I use a mixture of 3 lenses mostly

This Panasonic 25mm f1.7 lens is pretty great for tighter shots with a lot of viewable stars: $150

This Laowa 7.5mm f2 lens is pretty great for really wide shots: $500

This Laowa 17mm f1.8 lens is pretty great for a middle ground: $150

EDIT: Prices and spleling.

Saved https://web.archive.org/web/20190719165945/https://www.amazon.com/gp/product/B014RD6RC0/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&psc=1

PANASONIC LUMIX Professional 25mm Camera Lens G, F1.7 ASPH, Dual I.S. 2.0 with Power O.I.S., Mirrorless Micro Four Thirds, H-H025K (Black) https://www.amazon.com/dp/B014RD6RC0/ref=cm_sw_r_cp_apa_i_AmvWCb9VKJ583

Olympus M.Zuiko Digital ED 60mm F2.8 Macro Lens, for Micro Four Thirds Cameras https://www.amazon.com/dp/B0096WDK0K/ref=cm_sw_r_cp_apa_i_0mvWCbD7CJ089

I have also looked at these two I feel getting both suits my two goals best and they are different enough to justify getting both.

My first Panasonic camera came with the old 14-140. I love that lens and still use it, but, as /u/zatzai says, it's not very good indoors or in low light.

I would save the $150, get the dual lens kit for $749.95 - and then, when budget permits, get a faster lens (maybe the new 25mm f1.7).

Hope that's helpful and best of the holidays!

Also the 25mm (which I have and love) is on sale on Amazon right now for under $150. https://www.amazon.com/PANASONIC-LUMIX-MIRRORLESS-THIRDS-H-H025K/dp/B014RD6RC0/ref=sr_1_2?ie=UTF8&qid=1502482164&sr=8-2&keywords=panasonic+25mm