In 1994, I finished up a three-year lecturing contract at the National University of Singapore, and returned to Australia. That year saw the launch of the Netscape Navigator web browser (I wrote my first web page) and the opening of the Channel Tunnel between France and the UK (I was to take a train through that tunnel some years later). A plethora of movies was released – Stargate was one of the better ones:
The New Horizons spaceprobe, having given us some lovely pictures of Pluto in 2015, is on its way to the Kuiper belt. But what is the Kuiper belt? Named after Dutch-American astronomer Gerard Kuiper, the Kuiper belt is much like the asteroid belt, but much larger, about 15 times further out from the Sun, and far less well understood.
Initially, New Horizons is headed for the rock, or perhaps pair of rocks, (486958) 2014 MU69, which NASA has nicknamed Ultima Thule. The space probe is due to reach it on January 1st (which will be just short of 13 years after its launch). Currently, New Horizons is 6,360,000,000 km or 5.9 light-hours from Earth, and has recently completed a course-correction manoeuvre.
The InSight Mars lander launched yesterday from Vandenberg Air Force Base in California, and is scheduled to land on Mars on 26 November. There, it will probe beneath the surface and check for “marsquakes.”
Earlier, I wrote a post on why people know that the earth is round. Evidence such as star movement, the obscuring of distant objects by the earth’s curvature, and aircraft flight times shows that the earth is not flat:
In this post, I want to temporarily put on the “hat” of a flat-earther. They claim that the sun is a “spotlight” which travels across a circular flat earth like this:
That is at least a well-defined model, crazy though it might be, and therefore can be tested. Here is a computer render of the spring sun at sunset on that assumption (as seen from, say, San Francisco, at the moment that the sun disappears from view):
Three obvious problems with the flat-earth model are visible in this picture:
The sun is much too small: only 40% of its noontime diameter (because it is 2.5 times as far away as at noon)
The sun appears oval, rather than circular, because the “spotlight” is being seen obliquely (click to zoom if you can’t see the shape)
The sun is much too high in the sky (24° above the horizon)
In reality, of course, the sun at sunset is a circular disk that gradually slips under the horizon. Oops. No, the earth is not flat.