The Loeb Scale: Astronomical Classification of Interstellar Objects

TL;DR

The paper introduces the Loeb Scale, a 0-10 classification system for interstellar objects, enabling systematic, evidence-based assessment of their nature, including potential artificial origins, as detection rates increase.

Contribution

It presents the Loeb Scale, extending the Torino Scale, with defined thresholds and protocols for classifying interstellar objects and identifying potential technosignatures.

Findings

Loeb Scale effectively classifies known ISOs like 'Oumuamua and Borisov.

Provides a standardized framework for future ISO assessments.

Demonstrates applicability with real ISO case studies.

Abstract

The Vera C. Rubin Observatory is expected to increase interstellar object (ISO) detections from a few over the past decade to potentially one per few months, demanding a systematic classification scheme. We present the Loeb Scale, formally the Interstellar Object Significance Scale (IOSS), a 0-10 classification system extending the proven Torino Scale framework, to address ISOs' unique anomalies, including potential technosignatures. The scale provides quantitative thresholds for natural phenomena (Levels 0-3) and graduated protocols for increasingly anomalous characteristics (Levels 4-7), with Levels 8-10 reserved for confirmed artificial origin. Each level specifies observable criteria and response protocols. We demonstrate the scale's application using 1I/'Oumuamua (Level 4), 2I/Borisov (Level 0), and 3I/ATLAS (Level 4) as test cases. The Loeb Scale provides the astronomical community with a standardized framework for consistent, evidence-based and dynamic evaluation while maintaining scientific rigor across the full spectrum of possibilities as we enter an era of routine ISO encounters.