上一片刚见过黑洞有多贪吃。今晚🌌星空向导带你回家：我们就住在银河系里。银河中心，还藏着一个超大黑洞。Last leaf, you met how greedy black holes are. Tonight the 🌌 star guide takes you home: we live inside the Milky Way — and a supermassive black hole hides at its center.
第 1 步：两条旋臂的棒旋星系Step 1: A barred spiral with two arms
先看全家福——银河长什么样。First the family portrait — what does our galaxy look like?
银河系是棒旋星系（就是中间有根短棒的旋涡星系）。两条主旋臂从棒的两端旋出来。它直径约 10 万光年，装着 2000 亿颗恒星。光从一端走到另一端，要花 10 万年。The Milky Way is a barred spiral (a whirlpool galaxy with a short bar in the middle). Two main arms curl out from the bar's ends. It is about 100,000 light-years across and holds 200 billion stars. Light needs 100,000 years to cross it.
那我们住哪？抬头能看到家吗？So where do we live — and can we see home?
第 2 步：太阳住在郊区，夏夜能看见Step 2: The Sun lives in the suburbs — visible on summer nights
太阳在猎户座旋臂边缘，离中心约 2.6 万光年。夏夜往南看，天上那条发亮的带子，就是从侧面看的银河。城里灯太亮，去郊外看才清楚。The Sun sits on the Orion arm's edge, about 26,000 light-years from the center. On summer nights look south: that glowing band is our galaxy seen edge-on. City lights drown it — head somewhere dark.
家的正中心，住着上一片的老朋友。At the very center waits an old friend from last leaf.
第 3 步：银心藏着人马座A*Step 3: Sagittarius A* hides at the center
银河中心挤着几千万颗恒星。正中间，是超大质量黑洞人马座A*（约 400 万个太阳重）。它很远，吸不到我们。科学家已经给它拍过照片。Tens of millions of stars crowd the galactic center. Right in the middle sits the supermassive black hole Sagittarius A* (about 4 million Suns heavy). It is far away and cannot pull us in. Scientists have even photographed it.
🎮 银河定位（30 秒）🎮 Locate the Sun (30 seconds)
道理讲完了。星空向导摊开俯视图：读题点对地方，一共 4 关。Theory done — the star guide spreads the map. Read each clue, tap the right spot: 4 rounds.
一句话记住它：银河是两条旋臂的棒旋星系。太阳在边缘，离中心 2.6 万光年。直径 10 万光年，中心是人马座A*。Remember it in one line: the Milky Way is a two-armed barred spiral. The Sun sits on the edge, 26,000 light-years out. 100,000 light-years across, with Sagittarius A* at the center.
棒旋星系：中间短棒加两条主旋臂，直径约 10 万光年Barred spiral: short bar plus two main arms, about 100,000 light-years across太阳在猎户座旋臂边缘，离银心 2.6 万光年，夏夜往南看银河The Sun rides the Orion arm's edge, 26,000 light-years out; look south on summer nights银心是超大质量黑洞人马座A*，约 400 万个太阳重The center holds Sagittarius A*, some 4 million Suns heavy
内容参考 OpenStax 等公开教材，多来源核对 · AI 生成、人工审核 · 发现错误欢迎指正，帮这片叶子长得更好。Based on OpenStax and other open textbooks, cross-checked across sources · AI-generated, human-reviewed · Spotted a mistake? Tell us — help this leaf grow.
Back to tree
