wikiHow to Use Orion to Find Other Constellations

Constellations are hard to find if you're a novice who's never used a star map before. But a better idea is to star-hop: use one or two constellations with bright stars, and trace paths to other parts of the sky. Orion, with seven bright stars, can serve as your guide for a sky tour. Here are some paths to other constellations that you can follow when stargazing. Directions are written for the Northern Hemisphere only.

Steps

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    Know where Orion is. If you have no clue where it is, use star charts, such as David Levy's 'A Guide to Sky watching'. Google Sky Map is also an excellent resource for the novice.
    • Note that Orion is not visible around June. It is visible in the morning from July to mid-December, all night in late December, and in the evening from January to May.
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    Memorize the "corner" stars in Orion. Betelgeuse is in the top left, and glows reddish orange. It also fluctuates in brightness over the course of several years. To its right, Bellatrix (The Amazon Star) is a pale blue. Below Bellatrix is Rigel, a blue super-giant star, and the brightest in Orion. The dimmest star is Saiph, to the left of Rigel and below Betelgeuse. Between all of these stars is Orion's Belt, the three bright stars in a row.
    • Underneath Orion's Belt is his sword, which contains the Orion Nebula. This is a good target for binoculars or a small telescope.
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    Time to start navigating! Start with the two dimmest corner stars, Bellatrix and Saiph. Follow them up to encounter Aldebaran, the brightest star in Taurus, and the Pleiades, a bright star cluster. Follow them down to reach Beta Canis Majoris and Adhara. To the left of these stars is the sky's brightest star, Sirius. (The sun is actually the brightest.)
    • For this one, you can also follow Orion's belt right and left, respectively.
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    Continue following Saiph and Bellatrix and you will encounter Perseus, the hero from Greek mythology. In Perseus is Algol, one of a class of eclipsing variable stars, and the "Old Faithful" of the winter sky. Every 2.8 days its larger, dimmer companion obscures the brighter companion, leading to a sudden dimming that lasts for a few hours.
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    Follow Rigel and Betelgeuse, the two brightest stars in Orion, up to enter Gemini and view its two brightest stars, Castor and Pollux. (Fun fact: Pollux is the brightest star with a confirmed planet. Don't try to use a telescope to look for it though, it's not visible.) Castor is a sextuple star system, but only 3 can be seen in a telescope. One of these stars, YY Geminorium, is a variable.
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    Tracing from Bellatrix to Betelgeuse leads to Canis Minor, shining with the bright stars Procyon and Gomeisa. Procyon has a white dwarf companion, Procyon B, which can be seen in a large telescope. Going backwards leads to Aries, the Ram. Just under it is the dim constellation of Cetus. Omicron Ceti, known as Mira, is a long-period red giant variable. It changes from magnitude 8 (invisible) to magnitude 2 (one of the brightest stars in the sky) over 11 months.
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    Draw an imaginary line from Rigel to Bellatrix and you will crash into Capella, the brightest star in the constellation Auriga. Auriga rides Taurus, the Bull. Capella is the highest first-magnitude star, and is visible year-round from the northern US.
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    After you have found these stars, use them to find more constellations. A good set of star charts or Google Sky Map will help you out here.

Tips

  • Orion is rich with nebulae and star clusters. Use a telescope to see fine detail in the Orion Nebula, and binoculars to survey the Pleiades and Hyades.
  • Double stars are common too. Rigel has a sixth magnitude companion, as does Meissa, Orion's head.
  • Let your eyes dark adapt to see the wonders of the Milky Way in Orion, Taurus, and Gemini. A dark sky site is essential for such a survey.
  • The Orionid meteor shower peaks on October 21-22. On moonless nights, the peak can be up to 20 meteors per hour.
  • Use a laser to point out objects. If you don't have a laser, use a non-magnifying sight on a telescope to point out the general direction.

Warnings

  • Always be careful with lasers. Don't point at people or aircraft with lasers, because you could be fined.
  • Be careful when going outside and monitor your surroundings. Use a red flashlight to avoid ruining your night vision,
  • If you go to a dark sky site, make sure someone you trust knows where you're going. Have a full tank of gas and some supplies in case you need them.

Article Info

Categories: Astronomy