55 votes

Where did TRAPPIST-1a go?

To add to Rob's answer, I wanted to expand on where this naming convention comes from. The International Astronomical Union (IAU) is the organization which generally sets conventions and definitions. ...
zephyr's user avatar
  • 15k
42 votes
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Where did TRAPPIST-1a go?

The convention for planetary naming is that the closest planet to the star (if multiple planets are found at the same time) is named "star"b, then "star"c and so on. As correctly pointed out by Zephyr,...
ProfRob's user avatar
  • 152k
24 votes

Why are sometimes the brightest star of a constellation not named alpha?

Bayer didn't sort the stars strictly by brightness. He classified them as "first magnitude", "second magnitude" (and so on) following the traditional magnitudes assigned to stars ...
James K's user avatar
  • 121k
22 votes
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Did the temporary asteroid name DA₄₂ arise naturally and fortuitously (as a precursor to a Douglas Adams namesake)? Or did someone help it along?

There are other asteroids with provisional designation DA42. "D" means the second half of February, A=1 and 42 means the letters A-Z (excluding J) have been assigned 42 times. 2001 DA42 ...
James K's user avatar
  • 121k
17 votes
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Is there a relation with the noun planet and to be in a plane?

There is no close connection. Planet is from Greek asteres planetai meaning wandering stars (via Latin and French). Plane is from Latin planus meaning "level or flat". It is possible that both words ...
James K's user avatar
  • 121k
16 votes

Why nobody cares to give the nearest stars better names?

There are a thousand or so stars within 50 light years, most are very dim red dwarfs, and most are unexceptional. If we invent "names" then we would have to learn the names of all the stars. If we ...
James K's user avatar
  • 121k
13 votes
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Is there a name for a planet and its moons/satellites?

This question has been asked before on the Space Exploration page. In summary, the term used is system, e.g. the 'Jupiter system'.
christopherlovell's user avatar
10 votes
Accepted

What's the name of outside the cosmic horizon?

The outside is also the universe, the inside is just the observable universe.
A. C. A. C.'s user avatar
10 votes
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Why were two galaxies named "The Sagittarius Galaxy"? Is this common?

In addition to the Andromeda Galaxy (M31) and the Triangulum Galaxy (M33), the Local Group includes several dwarf galaxies named after the constellations in which they appear. In most cases, nearby ...
Mike G's user avatar
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10 votes
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Why was Neptune rather than Uranus chosen as an archetype?

NASA distinguishes four types of exoplanets: Gas Giant, Super-Earth, Neptune-like, and Terrestrial. The question asks why ice planets termed "Neptune-like" and not "Uranus-like". ...
B--rian's user avatar
  • 5,616
9 votes
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How to name planets outside our galaxy?

The original paper ( and a version on arXiv ) which this relates to does not seem to identify any actual planets. It's clear from the abstract that it is simply suggesting there is evidence that what ...
StephenG - Help Ukraine's user avatar
9 votes
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Ross 128 (What does the number mean?)

The number refers to the number in the catalog compiled by Frank Elmore Ross. From the Wikipedia article on Ross At Yerkes Observatory he was the successor to the late E. E. Barnard, inheriting ...
JohnHoltz's user avatar
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9 votes
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Why are sometimes the brightest star of a constellation not named alpha?

It's true that stars are lettered in order of brightness. So, in a constellation the brightnest star is (Alpha), the second brightest (Beta) and so on. That is why most of the First Magnitude Stars ...
Nilay Ghosh's user avatar
  • 4,462
8 votes
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What do the acronyms in "AT 2017 gfo" mean?

You are correct. The AT is short for Astronomical Transient. Next, follows the year and an arbitrary sequence of letters to uniquely identify the event, which is assigned by the Transient Name Server ...
James K's user avatar
  • 121k
8 votes
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Is there a database of all known star names/identifiers?

The closest service to what you are describing is the SIMBAD Astronomical Database from the Université de Strasbourg/CNRS. At the time I write this post, it contains 10.8M objects and 35.5M ...
Demitri's user avatar
  • 236
7 votes
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How did Biden become VP? (naming of 2012 VP113)

This has to do with how minor planets obtain provisional names (see also Wikipedia). The year is divided into 24 half months, with a particular letter associated with each one. Each of these half-...
HDE 226868's user avatar
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7 votes
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Why is it called "The LOFAR 'superterp'"? What is a terp, and what's so super about this one?

Terp is a Frisan and Dutch word meaning a low artificial hill for shelter during a high tide. See Wikipedia. Before dykes were built, farmstead were built on terpen to protect them from the frequent ...
James K's user avatar
  • 121k
7 votes

Why do we not call black holes black stars or dark stars?

The hypothetical object where gravity is so strong that even light cannot escape was indeed first called "dark star". It was first named as such by John Michell in the 1700s. See Wiki. Note ...
Allure's user avatar
  • 4,544
6 votes

Where did TRAPPIST-1a go?

The reason is because exoplanets orbiting a star are named in the order they were discovered, starting with the letter b. Sometimes, in a system with two stars, say Alpha Centauri, there are two stars,...
StellarExile's user avatar
6 votes
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Why was Uranus named what it was?

Herschel, the discoverer of the planet named it Georgium Sidus, "George's star" after his patron, King George III of Great Britain. The name was not popular outside of Great Britain, and there were ...
James K's user avatar
  • 121k
6 votes

Does IC 1101 have any name?

This answer is conjecture, but typically when an object has a nickname that identifier is used frequently as an alternative to the index number. In that case, you would expect a brief search through a ...
called2voyage's user avatar
  • 6,322
6 votes

Why is there no Proxima 'a' planet? I'm confused about the naming convention

Usually, the primary host star reserves the right to have the 'a' designation. Therefore 'a' never gets assigned to a planet. Please check the following post for a detailed explanation and some ...
mysterium's user avatar
  • 811
6 votes

What’s an Earth-Sun-Moon eclipse called?

The Sun won't pass between the Earth and the Moon in the near future, because the Sun is so much further away from the Earth, than the Moon. When the three are nearly co-linear, either the Earth ...
Connor Garcia's user avatar
  • 16.3k
6 votes
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What does "TON" in TON 618 stand for?

Tonantzitla Observatory. See https://en.wikipedia.org/wiki/TON_618 and https://en.wikipedia.org/wiki/Tonantzintla_Observatory
Pierre Paquette's user avatar
5 votes

Why nobody cares to give the nearest stars better names?

Almost without exception, the stars that have proper names are those stars that are visible to the naked eye. The rest require an instrument such as a telescope to be seen. While a proper name may ...
Mick's user avatar
  • 1,410
5 votes

Is having a surname which begins with the letter “A” a big advantage for a researcher in astronomy/astrophysics? Is changing our surname a good idea?

I would say that it matters not-at-all whether your name is Aardvark or Zygote. Astrophysicists are not stupid, we can see when a large author list has been alphabetised. If anything I would say it is ...
ProfRob's user avatar
  • 152k
5 votes

Why is Sagittarius A* called so?

The short answer is that, as George notes in his answer, there is no naming system for supermassive black holes. I wouldn't say they're really "named" after their host galaxies; more that when one ...
Peter Erwin's user avatar
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5 votes
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Why is Sagittarius A* called so?

Check this wiki link out. "The name Sgr A* was coined by Brown in a 1982 paper because the radio source was "exciting", and excited states of atoms are denoted with asterisks." There is no unified ...
George's user avatar
  • 334
5 votes
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How official is TNO 486958, 2014 MU69's new name Arrokoth?

The International Astronomical Union describes this minor planet naming process: Minor Planet Center assigns provisional designation MPC assigns permanent designation Discoverer suggests name IAU ...
Mike G's user avatar
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