Explanation:
No one knows for sure what caused this
signal.
There is a slight possibility that it just might
originate from an
extraterrestrial intelligence.
The bright colors on the blue background indicate that an
anomalous signal was received here on Earth by a
radio telescope
involved in a
Search for Extraterrestrial Intelligence (SETI).
A search for these signals is ongoing by
several groups including volunteer members of the
SETI League.
Time labels the vertical axis of the
above plot,
and frequency marks the horizontal axis.
Although
this strong signal was never positively identified,
astronomers have identified in it many attributes
characteristic of a more mundane and ultimately
terrestrial origin.
In
this case, a leading possibility is that the signal
originates from an unusual modulation between a
GPS satellite
and an unidentified Earth-based source.
Many
unusual signals from space remain unidentified.
No signal has yet been
strong enough or run long enough to be unambiguously
identified as originating from an
extraterrestrial intelligence.
