I’ve won a battle with the asteroids, and so am able to start adding them to “Astronomical Calendar 2017” – see the tab above. That is, as with the comets, I’ve worked out my way to use data from the Minor Planet Center, which you can see at http://www.minorplanetcenter.net/iau/MPCORB/MPCORB.DAT
(That file consists of orbital elements for thousands of minor planets, but I’m extracting only the first 999. You may notice that the first in the list is still Ceres, the first to be discovered. Including Ceres among the asteroids still makes sense, even though it also, because of its size, ranks in the new class of dwarf planets.)
I find that in 2017 these are the six asteroids that become brightest:
Asteroid number 4 Vesta (reaching magnitude 6.3)
7 Iris (6.9)
1 Ceres (7.5)
2 Pallas (8.3)
8 Flora (8.3)
20 Massalia (8.4).
Of the classic First Four (the ones discovered 1801-1807), Ceres is not at opposition (the most observable time) in 2017, so it is brightest at the end of the year as it approaches a January 2018 opposition. 2 Pallas with its strange orbit has an unfavorable opposition in October (it can be as bright as 6.5 at opposition or as dim as 10.6). 3 Juno, dimmest of the Four, ranges between opposition magnitudes of 7.6 and 10.3; this time, on July 2, it reaches only 9.9. 4 Vesta with its whitish surface becomes, as almost always, the year’s brightest asteroid, the only one to touch naked-eye findability, around its opposition in January.
Among those lower down the list (discovered from 1845 onward): 7 Iris is at one of its best oppositions, in October, because this is close to its perihelion on November 18. 8 Flora is at perihelion in July, so that it is brightening at the end of the year, only just before a January 2018 opposition. 20 Massalia has a favorable opposition in December because its perihelion is in February 2018.
So I have added to the “Astronomical Calendar 2017” timetable of events some asteroid dates: the oppositions and perihelia of the brightest ones, also the opposition of Juno and the brightening of Ceres at the end of the year. With time I’ll add an asteroid page with more detail and charts.
You have an Astronomical Calendar 2016 (I hope) to keep you abreast of sky events, and don’t need me to remind you that tomorrow, Monday Nov. 28, Mars is at its winter solstice.
Part of a diagram in the Mars section of Astronomical Calenda 2016. In late November, Mars’s north pole is leaning maximally away from the Sun, as happens for Earth in late December. The two planets’ north-hemisphere winters do not always happen close together.