An 8th-magnitude planetary nebula 3000 l.y. away in Aquarius, also known as NGC 7009. In shape it appears superficially similar to Saturn with its rings.
科学参考收录了60776条科技类词条，基本涵盖了常见科技类参考文献及英语词汇的翻译，是科学学习和研究的有利工具。