11/9/2023 0 Comments Systemrescuecd dban![]() ![]() He also measured stellar velocity and brightness to try to make a more accurate map. In the 1920s astronomer Jacobus Kapteyn took this a step further. The map they made from these observations shows the Milky Way appearing like a squashed inkblot, with the sun near the center. They assumed that if the Milky Way were elongated, stars would be more abundant along its long axis than through its shorter one. But it was also possible the nebulae might just be small clouds inside a Milky Way that comprised the entire universe.Įither way, the question remained: Where are we in the Milky Way? What position does our sun hold? To find out, in 1785 the sibling astronomers William and Caroline Herschel employed a clever method: they counted stars in various parts of the sky. No less a thinker than the philosopher Immanuel Kant speculated these objects might be “island universes,” of which the Milky Way was but one among many. In fact, as telescopes improved, astronomers spied in the sky many small spiral and elliptical “nebulae” (from the Latin word for “fog” or “mist”). But the fact that it appeared relatively flat suggested to 18th-century astronomers that the Milky Way was actually a disklike assemblage of stars that was more like a pancake than a sphere. If our galaxy were a huge spherical structure of stars with Earth near its center, its glow would be everywhere we look. The Milky Way’s true shape-implied in its riverlike path across the sky-offers an important clue as well. But the details of this structure stayed fuzzy (pardon my pun) until 1610, when Galileo confirmed the basic idea by turning his small telescope to the Milky Way and finding it was indeed composed of countless (at the time) stars. Over the centuries, many observers hypothesized that the Milky Way’s soft luminescence was the collective glow from myriads of stars that were too faint and close together in the sky to be individually distinguished. (Mea culpa: I’m guilty, too.)īut what causes this glow? Astronomers have learned that its subtle impression on the eye belies its true nature. The Greeks called it the galaktikós kyklos (“milky circle”), which is the source for the term “galaxy.” There’s amusing redundancy in calling it the Milky Way galaxy, as many do. The Romans called this feature in the sky the via lactea ( “milky road” or “milky way”), which is the origin of the modern name. The most famous of these, perhaps, is the Greek myth in which Hera pushes away the baby Heracles from her bosom, and her breast milk spills from horizon to horizon. ![]() But once you see it for yourself, you’ll appreciate why ancient people mythologized the heavenly scene. In fact, the glow of the Milky Way looks like steam coming from the teapot, which is tipped over and ready to pour boiling water onto the tail of Scorpius! But to our modern eyes, the stars instead uncannily resemble a teapot, with the bow depicting the spout. Sagittarius is generally depicted as the Archer, a centaur holding a bow. That’s one of my favorite sights in the sky, actually. This darkened cleft continues down toward the southern horizon even as the Milky Way itself broadens noticeably, and it bulges out into a lumpy blob near Sagittarius and Scorpius. Near Deneb, the brightest star in the constellation Cygnus, the Milky Way itself appears to split in half, separated lengthwise by a dark lane poetically (if not ominously) called the Great Rift. But for Northern Hemisphere observers, it’s brightest and easiest to spot in the summer, when it appears as a wide trail of light splitting the sky. It can be seen in the winter passing through familiar constellations such as Orion and Gemini. It spans 360 degrees of the sky in a continuous circle, enveloping Earth like a pale ring. Stretching from the northern horizon to nearly directly overhead and then down again to the southern horizon, a broad whitish swath will be visible across the sky, faintly glowing like a dimly seen celestial river. Yet from Earth they can barely be seen at all, even when you live inside of one.Ĭase in point: find yourself a dark spot over the coming week or two- where you can see stars down to magnitude 4.0 or 5.0 at a time when the moon rises late-and look up. They wield energies that dwarf our most fevered dreams. The universe is filled with immense structures of mind-crushing proportions. ![]()
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