Sixty Seconds: 0.0 in Celestial Coordinates

This video delves into how we define coordinates on Earth and in the sky, asks what lies exactly at 0.0 at the intersection of the equator and the prime meridian, and uses astronomy databases and sky surveys to search for a true 0.0 in space. It reveals near zero objects in catalogs, discusses the March equinox and the First Point of Aries, and ends with a fascinating look at the what3words location for the 0.0 point on the ocean and the broader message about catalog quality in astronomy.

Introduction: Why 0.0 Matters in Coordinate Systems

The video begins with a tour of terrestrial coordinates, explaining latitude and longitude, and why longitude requires a chosen zero point. Greenwich is the current standard for 0 degrees longitude, and the equator defines 0 degrees latitude. The discussion then moves to celestial coordinates, introducing declination as the sky's analogue to latitude and right ascension as the analogue to longitude, but measured in time rather than degrees.

Linking Earth and Sky Through Epochs and Equinoxes

The narrator ties the terrestrial reference frame to the celestial one by describing the March equinox, the First Point of Aries, and the intersection of the celestial equator with the plane of the ecliptic. This physical basis grounds how we define zero points in space, despite the sky's apparent motion due to the Earth’s precession and orbital motion.

Searching for 0.0 in the Cosmos

Using the NASA Extragalactic Database (NED) and the SIMBAD database, the search is run for coordinates 0.0 in celestial terms. The closest object is a WISE infrared source at 0h 0m 1.3s right ascension and +0° 0′ 11″ declination, which is near zero but not exact. A gamma ray source from the Fermi catalog initially looks promising because its reported position is 0.0 with a surprisingly small error, but the presenter remains skeptical and consults an expert for validation.

Data Quality and the Transience of the Sky

On checking the official Fermi target list, the 0.0 entry is no longer present, illustrating how catalogs can contain outdated or erroneous entries. The discussion broadens into a critical view of modern astronomy data pipelines, the importance of cross-checking catalogs, and the need to interrogate data to avoid false positives in transient astronomy.

Tools and Visualization

The video demonstrates Aladdin and a suite of sky surveys like DESI Legacy, XMM, and Chandra to visualize the intersection at 0.0, ultimately showing that there is nothing exactly on target in current imaging. The exchange with a colleague underscores how epoch changes and coordinate baselines must be updated over time, just like leap year corrections.

3 Words for the Sky

Finally, the three word addressing system What3Words is used to locate the tiny ocean buoy at 0.0, off the coast of Africa, humorously named Kull Island. The words prosecuting amplification showings illustrate how 3 by 3 meter cells can convey precise positions where conventional coordinates are cumbersome to communicate.

Takeaway

The main lesson is that even seemingly simple questions like what sits at 0.0 in space reveal the complexity of coordinate systems, the fragility of catalogs, and the value of careful cross-checking and robust data practices in astronomy.