This is the only whole-planet image we have of Neptune, taken by Voyager 2’s narrow angle camera in … [+]
Have you ever seen the eighth planet?
If not, Monday is the perfect time to hunt down any small telescope to take a peek at Neptune.
An “ice giant” planet, 17 times the mass of Earth, Neptune the most distant planet from the Sun in the solar system, but it’s normally very tricky to find in the night sky.
That’s not the case on Monday when it’s a mere 0.07° from Venus, the brightest planet of all, and easy to find in the night sky, though you will need to use a telescope or a pair of binoculars. While Venus is easy to see on any clear night this winter after sunset, Neptune is impossible to with the naked eye.
If you’ve never seen Neptune, this is your chance to see something 4.3 billion km from the Sun, and for your eyes to catch light that’s taken four light-hours to reach you.
The action will take place after sunset on Jan. 27 in the constellation of Aquarius.
How to find Venus and Neptune
The best time to see this celestial match-up is after sunset on Monday, January 27, 2020, when Venus will be 0.07° south of Neptune in the constellation of Aquarius, the water-bearer, in the south-western sky. Just above will be Phi Aquarii, a red giant star that’s visible to the naked eye. It all happens above a crescent Moon.
The following night, on Tuesday, January 28, 2020, Venus will have moved away from Neptune, but a crescent Moon will be closer to the pair of planets.
Here’s a close-up on the top of the constellation of Aquarius.
When is the best time to look at Neptune
This week is great because it’s easy to find. However, the very best time to look at any planet—if you don’t mind hunting—is when it is at its brightest, which is when it makes its closest approach to the Earth. Astronomers call this a planet’s “opposition”, and it occurs every year when an outer planet is opposite the Sun in the night sky when Earth is between the Sun and a planet in the solar system. For Neptune, that next occurs on September 11, 2020.
Here’s some more context for Neptune and Venus in the constellation of Aquarius.
What does Neptune look like through a telescope?
It may be a huge planet, but it’s orbiting from about 30 times further than the Earth-Sun distance. You need a minimum three-inch telescope on 100x (though preferably more like 200x) magnification or a 50 mm pair of mounted binoculars, and through them you’ll detect a pretty featureless, but clearly bluish planet. You may also see its Neptune’s biggest moon, Triton.
Neptune, combo of three pictures taken at differents dates (Photo by NASA/RDB/ullstein bild via … [+]
ullstein bild via Getty Images
“Oppositions” in 2020 for all the outer planets
Neptune appearing very close to Venus is a fluke of celestial mechanics. Here’s the very best dates in 2020 to point a telescope or a pair of binoculars at the outer planets (though a few weeks—even a month—either side will also get your bright views):
- Jupiter: July 14, 2020
- Saturn: July 20, 2020
- Neptune: September 11, 2020
- Mars: October 13, 2020
- Uranus: October 31, 2020
Wishing you clear skies and wide eyes