Sunrise Sunset why is that important in astronomy or amateur radio

Amateur Radio, Astronomy, Time

Sunset, Rockingham, NC 20150905 4:33 PM

Why is sunrise or sunset times important in amateur radio or astronomy?  I hope to develop this concept.

Sunrise and sunset is an important topic. Even in the Bible. According to the Blue Letter Bible sunrise is mentioned 13 times. Sunset is mentioned 11 times.  

A friend gave me a weather station for Christmas. and we were discussing some of the features and he mentioned that he had 17 minutes more observing time then I do.  He is a professional astronomer.  I got to thinking how could that be? He lives in Arlington, VA and I live in Wendell, NC.  Arlington is about 250 miles north of me.  So checking my internet go to source Time and Date  They bill themselves as the worlds top ranking website for time and time zones. I use to use a taxpayer funded service the Naval Oceanography Portal to get all my almanac data but according to their website they started a modernization in October 2019 and they have not completed this service. 

September 22, 2019 ISO 320 4.15mm, f/2.2 1/15s

In astronomy some objects we wish to see are not visible at certain times during the time period of sunrise or sunset.  That leads me to another aspect of the solar system activity. Civil Twilight, Nautical Twilight, Astronomical Twilight.

As you develop your astronomical skills certain things are visible at a certain number  before sunrise or are visible after sunset.   This is why you should always be mindful of the time of sunrise or sunset if you are looking to see a star or a planet. 

In amateur radio sunrise or sunset is also important to note.  The term Gray Line comes to importance. The best explanation I found is this article Working the Gray Line.

When you are up early in the evening or early in the morning (or middle of the night) beware of your safety. My friend that I mentioned earlier slipped on his dock before sunrise when he was going to take a sunrise picture and fell on his back.  He was sore but no broken bones.  While I was working for the Census Bureau last year one of their safety tips was to have three contact points as you are walking where possible. My friend did not get the picture.