Galaxy is a collection of interstellar dust, gas, dark matter, stars and their solar system which are all gravitationally bound. Our solar system is in 'MilkyWay' galaxy. And we know that there are nearly one hundred billion galaxies. Even in Vedas, there is discussion about galaxy, presence of billions of galaxies in universe, their rotation around its centre.
Galaxies Formation
Rig Veda 10.68.11
अभि श्यावं न कृशनेभिरश्वं नक्षत्रेभि∶ पितरो द्यामपिंशन् Ι
रात्र्यां तमौ अदधुजर्योतिरहन् बृहस्पतिर्भिनदद्रिं विदद्गा∶ ΙΙ
देवताओं ने अंतरिक्ष को नक्षत्रों से उसी प्रकार सुसज्जित किया, जिस प्रकार कृष्णवर्ण के अश्व को आभूषणों से अलंकृत किया जाता हैΙ उन देवताओं ने रात्रि में अंधकार को और दिन में प्रकाश को स्थापित कियाΙ ऐसे समय में ही बृहस्पति ने पर्वतों को विदीर्ण कर गौओं को प्राप्त कियाΙ
Physical forces (देवताओं) have made the space (galaxy) elegant with stars, similar to the way black horse is decorated with gold ornaments. Brihspati have set darkness in the night and light in the daytime. It has destroyed the darkness.
Galaxy Rotation
Galaxy Rotation
Atharvaveda 19.53.1
कालो अश्वो वहति सप्तरश्मि∶ सहस्राक्षों अजरो भूरीरेता∶ Ι
तमा रोहन्ति कवयो विपश्चितस्तस्य चक्रा भुवनानि विश्वा ΙΙ
जरारहित, प्रचुर पराक्रम से संपन्न ,सप्त रश्मियों और सहस्त्र चक्षुओं से युक्त कालस्वरूप अश्व जगत् रूपी रथ के वाहक हैंΙ समस्त लोक उस रथ के चक्र हैंΙ उस अश्वयुक्त रथ पर विद्वान ही आरूढ़ होते हैं Ι
Time in Vedas is called Kala(काल) is denoted as Aswa(अश्व). Aswa is a horse which runs continuously which represents the number seven. The word Bhuvanani(भुवनानि) refers to 'world' and Aswa - A+swa means time has no(A) tomorrow(swa). It refers to the meaning that time is continuous. As time never stops, thus it must have tremendous energy which is depicted by word Bhoorireta(भूरीरेता).
The word Sahasra Aksha(सहस्राक्षों) means multiplicity of axes. 'Viswa' means 'galaxy' in which there are innumerable solar systems. The word Viswah(विश्वा) refers to plural of galaxies. This refers to majorly two things - there are multiple number of galaxies and they are rotating about their axis.