Footsteps of Celestial Police

In the footsteps of the Celestial Police
a binocular activity

Eighteenth century astronomers felt there was something wrong with our solar system. They suspected that an unknown planet existed, moving between the orbits of Mars and Jupiter at 2.8 Astronomical Units from the sun. A curious mathematical relationship, eventually called the Bode–Titus Law (BT), had been formulated which seemed to satisfactorily describe the relative spacing of the planetary orbits. A planet was predicted orbiting 2.8 AU from the sun, but nothing was seen.


 Planetary Spacing Table

Planet   B–T value                     Actual value     
Mercury 0.40 AU 0.39 AU
Venus 0.70 0.72
Earth 1.00  1.00
Mars 1.60 1.52
?    2.80 ---
Jupiter 5.20 5.20
Saturn 10.0 9.54
Uranus 19.6 19.19

Neptune was not known at the time

European astronomers felt strongly enough about the reality of this unknown planet that they formed a team, nicknamed the “Celestial Police,” to search for it. However, a new body was spotted shortly before they could begin their organized search. On the night of January 1, 1801, team member Guiseppe Piazzi spied a starlike object that had moved slightly in the heavens near the Hyades and Pleiades star clusters. It was soon realized that it was a small body located near the same distance from the sun as was the “missing” planet predicted by the Bode-Titus law. It was eventually called Ceres.

Three other small bodies were discovered over the next few years, all lying about the same distance from the sun as Ceres. They were soon named Pallas, Juno, and Vesta. Over the years, many thousands of these small planetoids were found. They became known as asteroids.

Within the past twenty years, Ceres has been reclassified as a “dwarf planet.” The rest, including Pallas, Juno, and Vesta, are still referred to as asteroids.


Binocular Program: Tracking the dwarf planet Ceres in its orbital path

How to find Ceres (It will appear starlike, even through a telescope. Ceres will not be bright, but binoculars should reveal it.)
1.    Gaze high in the southeast 90 minutes after sunset. See Map A.
2.    Look for the Big Dipper. South of it lies the constellation Leo.
3.    The easternmost primary star of Leo is Denebola, the western star of the Spring Triangle..
4.    Place Denebola on the western edge of the field of binoculars. From there, move a complete field eastward.
5.    Use Map B to identify the stars 6 and 11 Comae Berenices. 6 and 11 are barely visible to the unaided eye in a dark, clear sky.
6.    Ceres will be located mid way between the pair on April 1. It will be seen as a star about the same brightness as the triangle of dim stars immediately east of 6 Com. See Map B.
7.    Each day Ceres moves slightly towards the west. By the end of April, it will be on the opposite side of the binocular field as Denebola. 

Track where it lies throughout April by noting where it lies. You will quickly discover that it moves!

Bright moonlight will significantly hamper observations before April 9.

 Click on the image to print/view PDF

Map A - Ceres 2023

Map B - Ceres 2023


    • Ceres is 588 miles (950 km) in diameter (27% that of our moon). 
    • At the beginning of April, it lies 151 million miles (245 million km) from Earth, and at the end of the month, it moves farther away to 167 million miles (270 million km).