The milky way is a spiral galaxy ; that is , if viewed from afar it would resemble a spiral 银河是螺旋星系;那是如果观看从它在远处会类似螺旋。
Spiral galaxies contain both young and old stars . in general , they are brighter than elliptical galaxies ：旋涡星系同时拥有年老和年青的恒星，它们通常比椭圆星系光。
80 17 through observation of the spiral galaxy m100 and thereby deducted that the universe was aged between 8 and 11 billions years old 8017 ，折算宇宙年大约在80亿至110亿年左右。
The largest disks are spiral galaxies such as our own milky way , which stretches more than 100 , 000 light - years across 最大的圆盘是像银河系般的螺旋星系，可横亘延伸远超过10万光年。
As far as astronomers can determine , elliptical galaxies rotate much more slowly than spiral galaxies or not at all 直到天文学家能够测定，椭圆星系自转要比旋涡星系慢的多或者根本不旋转。
Elliptical galaxies have much less dust and gas than spiral galaxies have , and few new stars appear to be forming in them 椭圆星系中的气体和尘埃比旋涡星系要少得多，貌似其内部也少有恒星诞生。
At least some elliptical galaxies , as well as the bulges and halos of spiral galaxies , may have arisen from such collisions 至少螺旋星系的核球与晕，以及某些椭圆星系，可能是由此种碰撞产生的。
That might happen during the collision of two spiral galaxies , which have lots of spare gas available for making new stars 这种情况很可能发生在两个螺旋星系碰撞时，因为这会剩下大量的气体，可供制造新的恒星。
Because gas constitutes only a few percent of the mass of spiral galaxies , modelers had neglected it to make the simulations more tractable 由于气体只占螺旋星系质量几个百分点，研究人员为使模拟较容易处理而将之省略。
There are sub - classes for the elliptical and spiral galaxies . they are summarized in the following figure that was first worked out by hubble 椭圆及旋涡星系皆可根据天文学家哈勃首创的方法再细分为次型，有如下图所示。
