SB 5.24.2
yad adas taraner mandalam pratapatas tad vistarato yojanayutam acaksate dvadasa-sahasram somasya
trayodasa-sahasram rahor yah parvani tad-vyavadhana-krd vairanubandhah surya-candramasav
abhidhavati.
Translation by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
The sun globe, which is a source of heat, extends for 10,000 yojanas [80,000 miles]. The moon extends for 20,000 yojanas [160,000 miles], and Rahu extends for 30,000 yojanas [240,000 miles]. Formerly, when nectar was being distributed, Rahu tried to create dissension between the sun and moon by interposing himself between them. Rahu is inimical toward both the sun and the moon, and therefore he always tries to cover the sunshine and moonshine on the dark-moon day and full-moon night.
Purport by His Divine Grace A. C. Bhaktivedanta Swami Srila Prabhupada:
As stated herein, the sun extends for 10,000 yojanas, and the moon extends for twice that, or 20,000 yojanas. The word dvadasa should be understood to mean twice as much as ten, or twenty. In the opinion of Vijayadhvaja, the extent of Rahu should be twice that of the moon, or 40,000 yojanas. However to reconcile this apparent contradiction to the text of the Bhagavatam, Vijayadhvaja cites the following quotation concerning Rahu; rahu-soma-ravinam tu mandala dvi-gunoktitam. This means that Rahu is twice as large as the moon, which is twice as large as the sun. This is the conclusion of the commentator Vijayadhvaja.