Adopted from Likutei Sichos of the Lubavitcher Rebbe Vol. XV: The Talmud [Sukah 29a] states that eclipses are Bad Signs for the World. The Talmud then elaborates on what can cause an eclipse:
An eclipse of the sun occurs for the following four reasons: For not having eulogized a chief judge (a chief judge is comparable to the sun, for [s]he enlightens and clarifies things for the community - Maharsha); for not having helped a betrothed maiden when she called for help (to save her from Ill treatment); for committing Adultery and for killing two brothers on the same day.Because of the following four reasons the moon and the stars eclipsed:
For committing Forgery, for False witnesses, for raising Goats and sheep in the Land of Israel (that is, for letting Goats and sheep pasture from other people’s fields - Rashi), and for cutting down fruit-bearing trees.
The Shaloh [Noach p.274b] explains that seeing the lunar eclipse implies a Bad Sign. Hashem would ascertain that the Jews would see it if they were Sinning. However, if they were not Sinning, Hashem would darken the sky so that the eclipse would not be visible.
This interpretation is not satisfactory, for the Talmud states: "For the following reasons an eclipse occurs" and not an eclipse is seen. The very occurrence of an eclipse is a consequence of the aforementioned Sins and not the sight of the eclipse. Furthermore, in cloudless locations such as Egypt [see Rashi Vayigash 47:10 and Vaera 7:17] the Jews would always be capable of seeing the eclipse, regardless of their behavior.
