The brightness to the naked eye of giant megaconstellations of satellites could create the greatest alteration to the night sky’s appearance in human history (see Nature https://doi.org/fdz8; 2020). This could have potentially catastrophic effects on celestial navigation by wildlife, and therefore on terrestrial ecology.
Migrating species such as birds, dung beetles and seals use stars as a source of directional information (see J. J. Foster et al. Proc. R. Soc B 285, 20172322; 2018). Some use bright objects as their main cue, and others rely on the starry sky’s centre of rotation, or the fainter band of the Milky Way.
Constellations of satellites can form coherent patterns that could affect night-time migrations in a similar way to the Milky Way, for example. Such errors would have a global effect on migratory populations. Their energy balance could be altered, with long-term repercussions for survival and reproduction, as has been found for excessive or misdirected light (S. A. Cabrera-Cruz et al. Sci. Rep. 8, 3261; 2018).
We call for astronomers and field biologists to identify and quantify the possible ecological effects of satellite megaconstellations. A regulatory framework could then be developed to control their proliferation, based on how species respond to spatio-temporal cues in the field.
Nature 586, 674 (2020)