Let’s continue our survey of Messier objects. Check some basic info if you’re joining late here. This is a nice one for the oncoming season of joy, Messier 10, actually discovered by the man himself:
image credit by Manfred Höcherl – https://cdn.astrobin.com/thumbs/Zgx0QoJLqpKZ_1824x0_kWXURFLk.jpg, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=97138684
Charles Messier didn’t actually see it this way in 1764. Like number nine, he described it as a “nebula without stars.” A decade later, Johann Bode, a German astronomer followed up: “nebulous patch without stars; very pale.” Fast forward another decade, William Herschel and his powerful telescope was able to tell the truth of it: “beautiful cluster of extremely compressed stars.”
From the vantage point of the Earth the core of stars presents as large as the right eye of the “man in the moon.” That makes it 83 light years across, by the best estimates.
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