Forty days after Easter Sunday …

Jesus – once dead – alive again:
for 40 days met, ate with them
but came and went with powers new
and taught them that they’d work to do
to tell and spread of all accomplished
on the cross, sin’s vice-hold vanquished.
But they must wait after He’d gone,
returned to heaven, for One to come –
His Spirit to equip, commission –
Christ ever with them in the mission.

And so that day He rose, soon hidden
by cloud, mysteriously returned to heaven.

Acts 1:4-11 in the Bible

So today is called Ascension Day, 40 days after Easter Sunday