Where Did the Sun Come From? [Q&A Livestream]

Fraser Cain (Universe Today)
Fraser Cain (Universe Today)Apr 19, 2026

Why It Matters

Identifying solar siblings refines models of the Milky Way’s formation, while understanding the Sun’s evolution and probe longevity guides future habitability studies and deep‑space mission planning.

Key Takeaways

  • Gaia maps billion stars, revealing Sun’s potential stellar siblings.
  • Matching orbital motion and chemical fingerprints identifies sibling candidates.
  • Black‑hole light bending could mirror Sun, but photon odds negligible.
  • Sun’s red‑giant phase will shift habitable zone to Jupiter’s moons.
  • Voyager 2’s RTG power dwindles, limiting instruments after five decades.

Summary

The livestream tackled the question “Where did the Sun come from?” focusing on how astronomers search for the Sun’s birth siblings and what that reveals about our star’s history.

Using data from ESA’s Gaia mission, researchers first filter stars that share a similar orbit around the Milky Way. They then compare the detailed chemical abundances—carbon, oxygen, iron, and other “metals”—derived from high‑resolution spectroscopy. Stars that match both criteria are flagged as potential solar siblings, and several candidates have emerged over the past five years.

The host also explored speculative ideas, such as using a black‑hole’s photon ring as a “time mirror” to view the Sun’s past—technically possible but practically impossible due to vanishing photon probabilities. He explained the Sun’s future red‑giant phase, noting that the habitable zone will migrate outward, briefly making Jupiter’s icy moons potentially water‑rich, while Voyager 2’s radioisotope thermoelectric generator is now running low, forcing shutdown of most instruments after nearly 50 years.

These discussions underscore how precise astrometric and spectroscopic surveys are reshaping galactic archaeology, how stellar evolution will redefine habitability in the distant future, and how aging power sources limit the lifespan of deep‑space probes, informing the design of next‑generation missions.

Original Description

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