Alien Invasion (Platt/Truant)7 books in series
Invasion Publisher's Summary
They are coming. The countdown has begun.
First visible only as blips on a telescope image, the discovery of objects approaching from Jupiter's orbit immediately sets humanity on edge. NASA doesn't even bother to deny the alien ships' existence. The popular Astral space app (broadcasting from the far side of the moon and accessible by anyone with Internet) has already shown the populace what is coming. So the news has turned from evasion to triage, urging calm and offering the few facts they have:
The objects are enormous, perfectly round spheres numbering in the dozens, maybe hundreds. They are on an approach vector for Earth. And they will arrive in six days.