Srimad-Bhagavatam: Canto 4 - Chapter 1 - Verse 13
Sanskrit:
एकदासीन्महासत्रदीक्षा तत्र दिवौकसाम् ।समाजो ब्रह्मर्षीणां च राजर्षीणां च सत्तम ॥ १३ ॥
ITRANS:
ekadāsīn mahā-satra-dīkṣā tatra divaukasāmsamājo brahmarṣīṇāṁ carājarṣīṇāṁ ca sattama
Translation:
Once upon a time King Pṛthu initiated the performance of a very great sacrifice in which great saintly sages, brāhmaṇas, demigods from higher planetary systems and great saintly kings known as rājarṣis all assembled together.
Purport:
In this verse the most significant point is that although King Pṛthu’s residential quarters were in India, between the rivers Ganges and Yamunā, the demigods also participated in the great sacrifice he performed. This indicates that formerly the demigods used to come to this planet. Similarly, great personalities like Arjuna, Yudhiṣṭhira and many others used to visit higher planetary systems. Thus there was interplanetary communication via suitable airplanes and space vehicles.