What should we call the Harvard EA office ?

You could call it the Harvard Square Effective Altruism Space. Relatedly, the New York one could be called the New York EA Space.  Makes them easy to find!

Aardvark

Pros:

• Appears first on any list or registry, and piques curiosity - may help in expanding the community
• Cute but weird animal name may attract both biologists and nerds in general
• Sounds a bit like "Harvard", so won't be hard to associate with it in memory
• Fun to let people try to say "Harvard Aardvark" repeatedly

Cons:

• Not immediately related to effectiveness or altruism. But all the astronomy names aren't either.

Edit: this comment is about 60% serious. Also I think amusing names are a good and underexplored direction.

"Supercluster", "Triangulum", or "Centaurus"?

Keeping with the astronomial theme of "Lightcone" and "Constellation", while also sounding like they could be the names for gatherings of people

Roughly in order of my preferences:

• Apollo, or Apollo Center/Hall/House/etc. God of "archery, music and dance, truth and prophecy, healing and diseases, the sun and light, poetry, and more," a "protector of the young" (appropriate given the university setting), and of course the namesake of the NASA mission, so a space connection. Maybe "Apollo Harvard Square" or something?
• Related: Athenaeum, which leans into the academic setting, the classical references throughout Harvard Square (street named "Appian Way," classical-inspired architecture in the Yard), and is a common name for libraries/centers of knowledge. Could also be "Harvard Square Athenaeum"
• Arete or Agathon, both of which mean some combination of excellence, integrity, and wisdom and are already the names of Harvard EA programs (which I think is good). (For some reason I like stuff that starts with an A; seems lively and high-priority.)
• Prospect. Looking-forward, which is nice given the location overlooking Harvard Square, longtermist/futuristic but in a horizon-scanning risk-aware way, and hopeful. "Prospect" as a noun has lots of meanings, all of which seem like good connotations, which is nice.
• Paradigm.
• Petrov Center, Petrov Hall, Petrov House
• Parfit Center, Parfit Hall, Parfit House
• Aphelion.
• Georgian House. "George" honors Henry George, the brilliant economist and philosopher that I'd consider a proto-EA (and whose adherents are way overrepresented in EA), and Curious George, since the world's only Curious George store was formerly in the same building (and the building is known as the "Curious George building" among alumni and longtime residents). Also a strong Harvard connection, as Georgian is the architectural style of the Yard and the official font of the university.
• The noun "Crossing" seems pretty good, since it's right in the square. Brattle Crossing, Kennedy Crossing, Apollo/Athena/Prospect/Petrov/Parfit Crossing, etc.
• I like Beacon from aL's comment and Aperture from Linch's. I would like Supercluster (and Andromeda) but seems too similar to Constellation
• Harvard Square Horizon. Sounds a bit like a daycare, but horizons are very apt for what we do
• Knowledge Commons, as in "Common Knowledge," though maybe this is like, too on the nose.

Syzygy.

It's a great word, it fits the astronomy theme, its meaning has EA significance, a synonym is "alignment," and DC-NYC-Boston-Oxford-London lie on a single great circle!!

• -itas words (that aren't as loaded as Utilitas), including
  • Gravitas
  • Vitalitas: vitality
  • Claritas: means brightness (the English derivative is clarity)
• Astronomy terms
  • Perihelion
  • Apogee
  • Astrolabe
• Mythology (add "House" or some other word to the end of these)
  • Daedalus: warned Icarus to not fly too close to the Sun
  • Cassandra: the cursed prophet (oof)
• Other nouns
  • Spire: looks sorta like a sorted heavy-tailed distribution. Also sounds like "aspire"
  • Cliffside: see above; also Precipice
  • Beacon or Lighthouse: guiding buildings. Also good because the office is near the top of the building.
• Some fun ones
  • Thinkcubator
  • The Margin at Harvard Square
  • Cambridge EA
  • Turing Testing Center

Some space-themed words I like:

1. Stardust

2. Aperture

3. Supernova

4. Earthshine

5. Equinox

6. Parallax

7. Planisphere

8. Quasar

9. Sunspot

10. Zenith

Cambridge Universal Utilities.

"Utilitas." Consequentialist vibes + similarity to Harvard's motto (sorry MIT!).

You could pick the name based on the "what3words" location description. For instance:  https://what3words.com/split.bigger.basket