How do you land robots on a rock? – ask the Japanese. PHOTO/GETTY IMAGES
SKY WATCH – NICK SAULT
Now we are on daylight saving we need to be out and about later to see a dark sky.
Not that you need a totally dark sky to see the bright planets that are still hanging around.
Jupiter and Venus still dominate the western sky and even in the dark blue of twilight they both stand out brightly.
In fact, they seem more prominent as the stars haven’t quite appeared.
Drink it in this month.
The show won’t last beyond the first week of November.
This week, when the sky is dark after 8.30pm but before those planets set, Jupiter, the less bright of the two, is currently a good mark for finding Scorpius.
I’m not in any way into astrology, but I do like to claim my birth constellation – silly, I know.
If you look due west where Jupiter sits above the horizon, the head of the Scorpion, which is a bit arrow-like, points directly at the planet from its position slightly higher in the western sky.
The scorpion then extends away up the sky to almost overhead, where its curly tail is quite obvious.
Scorpius is one of the few constellations that look anything like their name.
Our ancient friend Ptolemy must have run out of happy juice when he named that one.
Congrats to the Japanese.
They have actually landed little rovers on asteroid 162173 Ryugu.
Wow.
The asteroid is just under one kilometre wide and weighs a mere 450 million tonnes.
This means that its gravity is so low that the rovers can hop around on it.
That’s essential, as the thing is too rocky for wheeled rovers.
Fantastic the Japanese coming up with hopping rovers.
This is the first landing on a fast-moving asteroid.
Two more rovers will be deployed later and more exciting is that the rovers will deliver samples to the Hayabusa 2 mothership, which will return them to Earth in a couple of years from now.
Roll over NASA.
It’s interesting viewing the path of the probe.
I think a lot of people envision that you fire off your probe straight at the planet, comet, or asteroid you want to visit.
But in space, everything moves relative to everything else.
Also, no probe can carry enough fuel to drive it millions of kilometres across space.
The Japanese used the Earth’s orbital motion to fling the probe out to catch the asteroid in its wider orbit, as the asteroid is travelling slightly slower than the Earth.
That took more than four years.
On return, the opposite happens.
The probe is flung out by the asteroid’s motion, such that the faster Earth catches up on it for rendezvous. Amazing.
Next week: Our galaxy and why we are here.
