What is the most accurate way of propagation of Earth trajectory relatively to the Sun? I need to calculate the Earth-Sun distance. Is there any library on Python?
I've used before JPL Horizons, however, it's not useful for propagation for 1 Myr.
The La2010 long-term ephemeris Laskar et al. (2011), which is based on the INPOP numerical ephemeris integrated for 1 Myr, is valid for 250 million years before the present day and a unknown distance into the future. The authors note that due to chaotic motion in the Solar System, the accuracy degrades significantly beyond -50 Myr and likely a similar time into the future. The ephemeris is intended for paleoclimate and similar studies and provides the classical orbital elements which will need to be transformed into an Earth position or an Earth-Sun distance.