First pictures from Euclid satellite reveal billions of orphan stars

Number scale and wording

• Debate over “1,500 billion” vs “trillion”: some say “billions” downplays scale; others note that “trillion” and “billion” are historically ambiguous (long vs short scale), especially for non‑native readers.
• Several comments state that English‑language scientific literature effectively standardizes on the short scale, but others say long scale remains normal in many European languages and in some domestic scientific contexts.
• SI prefixes are cited as the true scientific standard; using powers of ten is seen as the least ambiguous.

Site availability and alternate sources

• The original university site repeatedly times out, attributed to an HN/“Slashdot” style traffic spike.
• Commenters share alternate news links and a Wikipedia entry on intergalactic stars for context.

Engineering, testing, and mission culture

• An engineer involved with Euclid describes propulsion and valves as especially difficult and safety‑critical, with very thorough testing and strong emphasis on heritage (“what already worked in space”).
• New methods are adopted only after heavy validation; progress can appear “glacial” from the outside.
• Personal reflections emphasize mixed stress and satisfaction, and the special value of science missions versus commercial or military spacecraft.

Orphan stars, rogue planets, and detectability

• Euclid observations: about 1.5 trillion stars in the Perseus cluster (240 million ly) and stars stripped from galaxies in Abell 2390 (2.7 billion ly).
• Unclear to some whether Euclid resolves individual intracluster stars at those distances or mainly measures their combined glow.
• Separate work with Euclid and other instruments has identified dozens of rogue planets in the Orion nebula (~1,500 ly); commenters infer many more rogue planets and stars in deep space that current instruments cannot see individually.
• One estimate suggests newly observed intracluster stars in Perseus might represent ~0.1% of the cluster’s total mass and ~1% of its stellar mass (rough, order‑of‑magnitude figures).

Life, habitability, and cosmic scale

• Some argue that with so many galaxies and stars it is hard to imagine life being rare; others stress how hostile space is and how many “jackpots” Earth seems to have hit (star type, orbit, magnetic field, gas giants, etc.).
• Counterpoints note we do not know the true probabilities, that oxygen is produced by life itself here, and that other biochemistries and environments might support life.
• Discussion of infinite‑universe arguments for duplicate Earths is challenged as requiring stronger assumptions; infinity alone doesn’t guarantee “everything happens.”

Expansion, isolation, and observability

• Comments describe a far future in which cosmic expansion leaves each galaxy effectively alone, with most galaxies forever unreachable even at light speed.
• Some emphasize that, despite this, records could preserve knowledge of now‑visible galaxies, though such information would still be trapped within each galaxy’s causal horizon.

Skies from orphan worlds and the distance ladder

• Multiple commenters explore what the night sky would look like from a planet orbiting an orphan star.
• One view: still star‑filled, with galaxies visible, just somewhat sparser.
• Another view: significantly emptier than our sky because there are few nearby stars outside galaxies; likely darker but not pitch black.
• People connect this to the “cosmic distance ladder”: parallax, Cepheid variables, supernovae, etc. A truly remote orphan civilization might find it harder to bootstrap accurate cosmology if nearby reference stars are too sparse.

Reactions and collaboration

• Many express awe at Euclid’s images and the sheer number of stars and planets implied, often referencing classic science fiction and humor.
• The Euclid Consortium’s scale—14+ countries, ~2,600 participants across many labs and disciplines—is highlighted as an inspiring example of international scientific cooperation.