March 2024: La Civiltà Cattolica, “To see the stars again: News from the Vatican Astronomical Observatory”

Vatican observatory astronomer Fr. Jean-Baptiste Kikwaya Eluo, S.J. studies solar system objects that are not so distant. His research interest is Near-Earth Objects (NEOs). NEOs are asteroids and comets whose orbits cause them to draw close to Earth’s orbit—closer than Venus, the planet whose orbit is least distant from Earth. That nearness to Earth, and thus the possible hazard NEOs pose to Earth and the need to be able to protect Earth from them, are what motivates Fr. Kikwaya Eluo to study them.

Recently Kikwaya Eluo, together with his collaborators, conducted observation campaigns that resulted in the observation and reduction and analysis of data from more than twenty objects. The results for four of these objects, for example, were reported in the paper “Lightcurves and Colors of Four Small Near-Earth Asteroids: 2020 BV14, 2023 HH3, 2023 HT3, 2023 KQ” by Kikwaya Eluo and C. W. Hergenrother, published in the Minor Planet Bulletin (volume 50, number 4) at the end of 2023.

Kikwaya Eluo and Hergenrother observed the four objects using the Vatican Advanced Technology Telescope (VATT), located on Mt. Graham in Arizona (USA). They mapped out each object’s “lightcurve”. The lightcurve is the periodic variation in the apparent brightness of an object. As the object rotates, different parts of it face the Sun and the Earth. Therefore, it reflects varying amounts of the Sun’s light toward Earth. The lightcurve of the NEO 2023 KQ is shown here. These variations reveal that 2023 KQ completes one rotation every 42 minutes (0.70 hours).

Observing a NEO’s colors allows us to learn something about its composition. Kikwaya Eluo and Hergenrother passed the light that the VATT gathered from 2023 KQ through various filters (known as B, V, R, and I filters, for “blue”, “visible”, “red” and “infrared” wavelengths of light). They looked at the differences between the different filters (B compared to V, V compared to R, etc.), charted those differences, and then compared the results to other types of asteroids and to laboratory results obtained from meteorites. Meteorites are perhaps the nearest of NEOs; they are material from objects in space that entered Earth’s atmosphere and made impact with Earth’s surface. The filter results suggest that 2023 KQ belongs among the S-type (siliceous) objects.

The objects that enter Earth’s atmosphere are also part of Fr. Jean-Baptiste Kikwaya Eluo’s work. He is involved in a project to study bright meteors, in collaboration with the Paris Observatory. Meteors are commonly known as “shooting stars”; astronomers call exceptionally bright meteors “fireballs”. The fireball project uses a camera network to image these objects. The goal is to learn about their trajectories and size distribution, and to be able to find meteorites on Earth’s surface that came from them. If meteorites from a given fireball can be found, that will then allow for laboratory study of them, with the knowledge of what particular group or “meteor shower” they came from—linking the physical characteristics of these objects to meteor showers, and then to their parent bodies (asteroids or comets).

Fr. Kikwaya Eluo also tracks fainter meteors, using cameras at the Vatican Observatory. The images from these can be seen by anyone who visits the Vatican Observatory website, https://www.vaticanobservatory.org/meteor-cams/. The goal is to study the physical characteristics of these very faint “shooting stars”, working to determine their densities and to compute their orbits and determine the sorts of parent bodies from which they came. This information could be useful in studying the formation and evolution of the solar system; “shooting stars” are thought to be remnant material from the early days of the solar system.

Of course, multiple cameras running all the time means much opportunity for malfunctions. Kikwaya Eluo has to work to keep the cameras running. Something as simple as a faulty switch connecting a camera to the internet can interrupt the data flow. Happily, among Fr. Jean-Baptiste Kikwaya Eluo’s abilities is the ability to solve such problems!