Radio waves can be polarized in various ways - your typical "whip" style antenna is vertically polarized - hence the antenna is vertical. A TV antenna is horizontally polarized. A circularly polarized antenna may have a spiral shape and the radio wave does the following:
Specifically, given that this is a circularly polarized plane wave, these vectors indicate that the electric field, from plane to plane, has a constant strength while its direction steadily rotates. (Wikipedia)
This is somewhat unusual for radio waves from distant stars or rotating pulsars and the like (according to the article).
Astronomers are divided about what this all means, with some (the author of the article I linked to) believing that the source is much closer than the radio shifting would indicated (that they are not 3 billion light years away but perhaps only a few thousand, or a few hundred, or just outside our solar system).
This is stuff you don't usually hear about and I thought it was quite interesting.
Here is another more recent story on the subject: https://www.newscien...close-to-earth/
Edited by SteampunkScientist, 16 October 2018 - 02:44 PM.