https://msi.nga.mil/Publications/APN
The American Practical Navigator, first published in 1802, was billed as the “epitome of navigation” by its original author, Nathaniel Bowditch. The text has evolved with the advances in navigation practices since that first issue and continues to serve as a valuable reference for marine navigation in the modern day.
The publication describes in detail the principles and factors of navigation, including piloting, electronic navigation, celestial navigation, mathematics, safety, oceanography and meterology. It also contains various tables used in typical navigational calculations and solutions, including the formulas used to derive the tabular data. Many of these solutions can also be found using the on-line calculators located in the Nautical Calculators section of this Web site.
The 2019 edition, updated to June 2021, of the American Practical Navigator is published in two volumes, which can be downloaded as complete PDF documents by selecting the hyperlinks below.
https://spaceweather.com/
CME IMPACT SPARKS NORTHERN *AND* SOUTHERN LIGHTS: A CME struck Earth's magnetic field yesterday, March 15th. The impact was so strong, it sparked auroras over both ends of our planet. First, the south:
"Red auroras lit up the skies above Lake Ellesmere, New Zealand," reports photographer Mike White. "A strong glow persisted for an hour or so on the southern horizon with occasional periods of bright rays extending upwards." Second, the north:
Roman Banas photographed these red auroras near Bydgoszcz, Poland, almost 18,000 km away yet remarkably similar to the display in New Zealand. "You could see the rays with the naked eye," says Banas. "It was strongest around midnight."