4 ms·

The pleiades are a cluster, not a constellation.

by tiagod 6y ago

SkittyDog 6y ago
From the WP article, under "Folklore and Mythology": "Some Greek astronomers considered them to be a distinct constellation, and they are mentioned by Hesiod's Works and Day..." (emphasis mine) So it would appear that they are both. FWIW, I have no idea if there is some astronomical technical jargon distinction between "constellation" and "cluster" that inspires your comment. But to this layman, your correction comes across as pedantix and unnecessary. The term "constellation" is clearly valid, here, as common everyday English is spoken.
- cedilla 6y ago
  There is a difference: a constellation is an area of the sky where some stars appear to belong together to form an image. Their actual distance may be vast. A cluster on the other hand actually is a group of stars that formed from the same material and are thus very close to each other. So there is a difference, but it's only a problem to interchange the terms the other way round.
  - macintux 6y ago
    Given that the Pleiades are, I believe, the only cluster in the sky large enough to act as a constellation, it's certainly not irrational to treat them as both. A cluster could be treated as a constellation, but not vice versa.
    - sellyme 6y ago
      This is exactly what the comment you are replying to said.
  - SkittyDog 6y ago
    While I'm glad to be educated about the technical definition, it's still not even remotely relevant. The point is to whether the commonplace usage is worthy of correction... In this case, the correction adds nothing of value to the discussion. It struck me as a rude, self-aggrandizing gesture by an adult who should know better.
umanwizard 6y ago
What is the difference?
- antonvs 6y ago
  A cluster is a collection of stars that are relatively close to each other in space, and bound together as a group by each other's gravity. For example, the Pleiades has a core radius of only about 8 light years, and almost all of the 1,000+ stars in the cluster are within a volume of radius 43 light years. A constellation is a two-dimensional region of the sky, more like counties or states on a map. The "celestial sphere" is divided into 88 constellations, which were chosen essentially arbitrarily, based largely on historically significant apparent groupings of stars. Stars in a constellation superficially look to us as though they're near each other, but they may be very different distances from us, because we see the night sky as two-dimensional. For example, one of the furthest stars visible to the naked eye is over 16,000 light years away, called V762 Cas in the constellation Cassiopeia. Cassiopeia also contains many other stars that are much closer to us, such as Eta Cassiopeiae which is just 19.4 light years away, practically a next-door neighbor.

The pleiades are a cluster, not a constellation.

by tiagod 6y ago

The pleiades are a cluster, not a constellation.

From the WP article, under "Folklore and Mythology": "Some Greek astronomers considered them to be a distinct constellation, and they are mentioned by Hesiod's Works and Day..." (emphasis mine) So it would appear that they are both. FWIW, I have no idea if there is some astronomical technical jargon distinction between "constellation" and "cluster" that inspires your comment. But to this layman, your correction comes across as pedantix and unnecessary. The term "constellation" is clearly valid, here, as common everyday English is spoken.

cedilla 6y ago
There is a difference: a constellation is an area of the sky where some stars appear to belong together to form an image. Their actual distance may be vast. A cluster on the other hand actually is a group of stars that formed from the same material and are thus very close to each other. So there is a difference, but it's only a problem to interchange the terms the other way round.
- macintux 6y ago
  Given that the Pleiades are, I believe, the only cluster in the sky large enough to act as a constellation, it's certainly not irrational to treat them as both. A cluster could be treated as a constellation, but not vice versa.
  - sellyme 6y ago
    This is exactly what the comment you are replying to said.
- SkittyDog 6y ago
  While I'm glad to be educated about the technical definition, it's still not even remotely relevant. The point is to whether the commonplace usage is worthy of correction... In this case, the correction adds nothing of value to the discussion. It struck me as a rude, self-aggrandizing gesture by an adult who should know better.

umanwizard 6y ago

What is the difference?

antonvs 6y ago
A cluster is a collection of stars that are relatively close to each other in space, and bound together as a group by each other's gravity. For example, the Pleiades has a core radius of only about 8 light years, and almost all of the 1,000+ stars in the cluster are within a volume of radius 43 light years. A constellation is a two-dimensional region of the sky, more like counties or states on a map. The "celestial sphere" is divided into 88 constellations, which were chosen essentially arbitrarily, based largely on historically significant apparent groupings of stars. Stars in a constellation superficially look to us as though they're near each other, but they may be very different distances from us, because we see the night sky as two-dimensional. For example, one of the furthest stars visible to the naked eye is over 16,000 light years away, called V762 Cas in the constellation Cassiopeia. Cassiopeia also contains many other stars that are much closer to us, such as Eta Cassiopeiae which is just 19.4 light years away, practically a next-door neighbor.