此外，科学家还发现一些完全不同类型的行星：有的像木星大小却更靠近恒星；有的围绕双星或已 死亡恒星运转；有的表面覆盖熔岩；有的密度如泡沫塑料；还有的云层由宝石组成。不同类型行星都为 研究行星形成条件提供了信息，并有助判断类地行星的普遍性及潜在分布区域，对探索宇宙生命至关重 要。 目前，直接拍摄到的系外行星不到100颗，多数行星光线微弱，被母星的光芒所掩盖。探测其他行 星一般采用的是间接法，如凌日法等。大多数候选行星需要后续观测确认，这也是档案中存在大量候选 行星的原因。 科学家已在整个银河系中发现了数千颗系外行星（太阳系外的行星）。大多数行星只能通过间接方式进 行研究，但科学家们知道，它们种类繁多，正如这幅艺术概念图所描绘的那样，既有小型岩石行星和气 态巨行星，也有富含水的行星，甚至还有温度如恒星的行星。图片来源：NASA官网戈达德太空飞行中 心 美国国家航空航天局（NASA）官网日前称，其监测并确认的太阳系外行星数量突破6000颗。 NASA在声明中表示，他们会持续将确认的行星加入统计，因此没有哪一颗单独被视为是第6000颗。目 前，还有超过8000颗候选行星等待确认。 银河系中可能存在数十亿颗行星，但要确认 ...

Core Points - The James Webb Space Telescope (JWST) has found evidence of an exoplanet named TWA 7b, which, if confirmed, would be the first exoplanet discovered through direct imaging by the telescope and the smallest exoplanet discovered using this method to date [1][2] - TWA 7b orbits a star located approximately 110 light-years away, with a mass similar to that of Saturn [1] - The discovery was made by an international research team, which published their findings in the journal Nature [1] Methodology - The JWST previously discovered exoplanets primarily using the transit method, which detects the dimming of a star as a planet passes in front of it [1] - Direct imaging is more challenging due to the overwhelming signals from the host star, making the detection of exoplanets more complex [1] - The research team utilized the mid-infrared instrument on the JWST to filter out signals from the TWA 7 star, identifying a signal source in the surrounding dust ring that matched theoretical predictions for the presence of a planet [1] Significance - If further research confirms TWA 7b as an exoplanet, it would represent a significant advancement in the sensitivity of direct imaging techniques, with its mass being about one-tenth of the previously smallest exoplanet discovered through this method [2]