...Next time in a dark anchorage look at the other boats mast head lights and you will see what he's talking about right away. Meggi once mistook one for Venus and was waiting for it to get a bit higher so she could practice with the sextant.
While I have no doubt that Meggi once mistoook an LED anchor light for Venus, realize that you were both anchored, and therefore not likely to collide with the other vessel.
Bubblehead has it right, in that if another vessel confuses your LED steaming light with a star, they are within the 135° arc, while overtaking you.
(a) Notwithstanding anything contained in the Rules of Part B, Sections I and II any vessel overtaking any other shall keep out of the way of the vessel being overtaken.
(b) A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5 degrees abaft her beam, that is, in such a position with reference to the vessel she is overtaking, that at night she would be able to see only the sternlight of that vessel but neither of her sidelights.
Unless they are approaching you from directly (±5°) behind, the LED stern light should appear to move much more rapidly than a star. Regardless, the LED stern light should appear BELOW the horizon, and well below the plane of visible stars.
This does, however, provide a good argument for investing in an AIS class B transponder....