Mitchell, hey. The latest Celestia 1.6.1 release is available for MacOS and Windows.
But if you're talking about the development 1.7.0 version, then the release was not yet, but when the time comes, I hope that release will be for Windows, Linux and MacOS.
Admin of celestiaproject.net.PC: Lenovo IdeaPad Z570
. Intel Core i5-2450M CPU @ 2.50GHz, 8 ГБ ОЗУ, NVIDIA GeForce GT 540M, Windows 10 Enterprise x64.Phone: iPhone 7 Plus 128 Gb.