In this connection, the darkness occurring before the full moon, the lunar eclipse, can be explained as being another planet, known as Rahu. According to Vedic astronomy, the Rahu planet, which is not visible, is accepted. Sometimes the Rahu planet is visible in the presence of full moonlight. It then appears that this Rahu planet exists somewhere near the orbit of the moon. The failure of modern moon excursionists may be due to the Rahu planet. In other words, those who are supposed to be going to the moon may actually be going to this invisible planet Rahu. Actually, they are not going to the moon but to the planet Rahu, and after reaching this planet, they come back. Apart from this discussion, the point is that a living entity has immense and unlimited desires for material enjoyment, and he has to transmigrate from one gross body to another until these desires are exhausted.

Srimad-Bhagavatam Purport 4.29.69
A.C. Bhaktivedanta Swami Prabhupada

--

siras tv amaratam nitam
ajo graham aciklpat
yas tu parvani candrarkav
abhidhavati vaira-dhih

Translation
Rahu's head, however, having been touched by the nectar, became immortal. Thus Lord Brahma accepted Rahu's head as one of the planets. Since Rahu is an eternal enemy of the moon and the sun, he always tries to attack them on the nights of the full moon and the dark moon.

Purport
Since Rahu had become immortal, Lord Brahma accepted him as one of the grahas, or planets, like the moon and the sun. Rahu, however, being an eternal enemy of the moon and sun, attacks them periodically during the nights of the full moon and the dark moon.

Srimad-Bhagavatam 8.9.27
A.C. Bhaktivedanta Swami Prabhupada
--

a-kalanka gauracandra dila darasana
sa-kalanka candre ara kon prayojana
eta jani' rahu kaila candrera grahana
krsna krsna hari name bhase tri-bhuvana

Translation
When the spotless moon of Caitanya Mahaprabhu became visible, what would be the need for a moon full of black marks on its body?

Considering this, Rahu, the black planet, covered the full moon, and immediately vibrations of "Krsna! Krsna! Hari!" inundated the three worlds.

Purport
According to the Jyotir-veda, a lunar eclipse takes place when the Rahu planet comes in front of the full moon. It is customary in India that all the followers of the Vedic scriptures bathe in the Ganges or the sea as soon as there is a lunar or solar eclipse. All strict followers of the Vedic religion stand up in the water throughout the whole period of the eclipse and chant the Hare Krsna maha-mantra. At the time of the birth of Lord Caitanya Mahaprabhu, such a lunar eclipse took place, and naturally all the people standing in the water were chanting Hare Krsna, Hare Krsna, Krsna Krsna, Hare Hare/ Hare Rama, Hare Rama, Rama Rama, Hare Hare.

Caitanya-Caritamrita Adi 13.91-92
A.C. Bhaktivedanta Swami Prabhupada