The Leo Trio
Image Credit & Copyright: Francis Bozon
Explanation: This popular group leaps into the early evening sky around the March equinox and the northern hemisphere spring. Famous as the Leo Triplet, the three magnificent galaxies found in the prominent constellation Leo gather here in one astronomical field of view. Crowd pleasers when imaged with even modest telescopes, they can be introduced individually as NGC 3628 (right), M66 (upper left), and M65 (bottom). All three are large spiral galaxies but tend to look dissimilar, because their galactic disks are tilted at different angles to our line of sight. NGC 3628, also known as the Hamburger Galaxy, is temptingly seen edge-on, with obscuring dust lanes cutting across its puffy galactic plane. The disks of M66 and M65 are both inclined enough to show off their spiral structure. Gravitational interactions between galaxies in the group have left telltale signs, including the tidal tails and warped, inflated disk of NGC 3628 and the drawn out spiral arms of M66. This gorgeous view of the region spans over 1 degree (two full moons) on the sky in a frame that covers over half a million light-years at the trio’s estimated distance of 30 million light-years. Of course the spiky foreground stars lie well within our own Milky Way.
Tomorrow’s picture: antikythera
说明: 在春分前后的北半球春天，这群热门的星系在入晚后即升起。著名的狮子三重星系，为聚集在狮子座单一视野内的3个壮丽星系。编录号分别是NGC 3628 (右)、M66(左上)、和M65 (下)的这群星系，是用中小口径望远镜观星的热门标的。它们都是大螺旋星系，不过由于盘面和我们视线的夹角不同，它们在外观上颇有差异。其中，名为汉堡星系的NGC 3628为侧向，有尘埃带切过鼓胀的星系盘。而M66和M65的视倾角都够大，所以我们能见到它们的旋臂结构。这群星系之间的重力互扰，造就了一些明显的特征景观，包括NGC 3628的潮汐尾和扭曲膨胀的星系盘，以及M66被拉长的螺旋臂。这片宽超过1度（2个满月）的壮丽视野，以狮子三重星系3千万光年远的估计距离来换算，涵盖50多万光年的区域。很明显的，带着星芒的前景恒星，近在我们的银河系之内。