I think this picture is badly put together. It is labelled as if the centre is the past, and left and right are the present
I think this criticism is somewhat unfair, there are nested arcs of dashed lines centered around the past and these lines intersect with the times on either side delineating specific regions corresponding to a time period, both the lines and the timescales have complementary colour coding for particular stretches of time. Certain of the lines are also labelled with specific events associated with a particular time period.
It's more accurate to think of the whole outer rim of the diagram as the present.
That is in fact exactly what the diagram shows.
There are plenty of elements which obviate your initial objection if you give the diagram more than a cursory glance.
TTFN,
WK