Srimad-Bhagavatam: Canto 5 - Chapter 1 - Verse 8

Sanskrit:

उत्तरोत्तरेणेलावृतं नील: श्‍वेत: श‍ृङ्गवानिति त्रयो रम्यकहिरण्मयकुरूणां वर्षाणां मर्यादागिरय: प्रागायता उभयत: क्षारोदावधयो द्विसहस्रपृथव एकैकश: पूर्वस्मात्पूर्वस्मादुत्तर उत्तरो दशांशाधिकांशेन दैर्घ्य एव ह्रसन्ति ॥ ८ ॥

ITRANS:

uttarottareṇelāvṛtaṁ nīlaḥ śvetaḥ śṛṅgavān iti trayo ramyaka-hiraṇmaya-kurūṇāṁ varṣāṇāṁ maryādā-girayaḥ prāg-āyatā ubhayataḥ kṣārodāvadhayo dvi-sahasra-pṛthava ekaikaśaḥ pūrvasmāt pūrvasmād uttara uttaro daśāṁśādhikāṁśena dairghya eva hrasanti.

Translation:

Just north of Ilāvṛta-varṣa — and going further northward, one after another — are three mountains named Nīla, Śveta and Śṛṅgavān. These mark the borders of the three varṣas named Ramyaka, Hiraṇmaya and Kuru and separate them from one another. The width of these mountains is 2,000 yojanas [16,000 miles]. Lengthwise, they extend east and west to the beaches of the ocean of salt water. Going from south to north, the length of each mountain is one tenth that of the previous mountain, but the height of them all is the same.

Purport:

In this regard, Madhvācārya quotes the following verses from the Brahmāṇḍa Purāṇa: It appears from these verses that aside from the sun and moon, there is an invisible planet called Rāhu. The movements of Rāhu cause both solar and lunar eclipses. We suggest that the modern expeditions attempting to reach the moon are mistakenly going to Rāhu.