The Night Sky This Month: February 2015

Jupiter and Jovian Moons

Moon Phases

Have a look here anytime you want to know the Moon phases. The site that provides it also has plenty of facts about the Moon available. There is even a free app available for iPhone or for Android in their appropriate stores that let you track both the Moon and the Sun activity.

Planets

As the Sun sets you’ll see the Evening Star (Venus) in the western sky, following along after the Sun. Hot on its trail is Mars, which will set soon afterwards. But don’t be disappointed when they’re gone; Jupiter is heading up the sky from the east, and will be with you all night. And the great thing about Jupiter this month is that it’s in opposition to the Sun on the 6th of February, from Earth’s point of view, so it’s positively brilliant. It’s also as close as it’s going to get until the year 2019 – only a little over four astronomical units (AU, the distance between Earth and the Sun) away from us.

This would be a great time to catch a glimpse of the four biggest Jovian Moons (sometimes called the Galilean moons because they were named after their discover Galileo) since they’ll be as bright and well-lit as their parent planet. I’ve seen them in binoculars, as four little dots in a row which is interesting enough, but I still prefer a telescope; you can track their motions over several evenings for fun.

It is interesting to reflect that if you were at Jupiter, looking back at Earth (although not at opposition where the Sun is right behind it and rather blinding), our Moon would be just as visible as those of Jupiter, since they’re all approximately the same size. Only the moons Titan and Triton (Saturn & Neptune, respectively) are of similar size. Most of the rest of the moons in the solar system are smallish.

Planets don’t Twinkle

If you’re ever having trouble distinguishing between a star and a planet remember the title above. The light from our own Sun, reflected from a planet and coming back to us has traveled such a (relatively) short distance that it is still coherent. Light traveling from a point source that is many light years away from us is more easily disrupted by the eddies in our atmosphere. That’s the guide: stars twinkle, planets don’t.

Later in the month on the 20th and 21st Mars and Venus will be right next to that sliver of the Moon, getting as close to each other (in our view) as they’re going to be until about two years down the road. This month they’ll be so close that you’ll be able to watch both of them at the same time with binoculars. Of course I always recommend a telescope especially on one of these still, clear, winter nights when viewing is so incredible. The cold, dense, thick, heavy air doesn’t twist and writhe as much making the stars steadier.

Orion Constellation Stars
Orion Constellation Stars

Brightest Stars Seen In Orion

The brightest stars in February can be found in Orion, with all the stars of this constellation very bright and of either first or second magnitude. Hanging below the three stars which represent mythological giant’s belt, is Orion’s sword which is seen as three stars hanging in a vertical row. The middle of the three, however, is not a star but in fact a 12 light years across cloud of dust and gas called the Great Orion Nebula, a huge nursery for new stars.

A Dullish Month

There are a couple of Asteroids that are visible right now. On Feb 1st Pallas should be at RA 17h 02m 15s/Dec +05° 12’ 38” and Juno should be at RA 08h 29m 38s/Dec +4° 06’ 55” which are both at opposition and fairly bright (for asteroids) but they’re Class Five observing skills, for people with plenty of experience and decent telescopes. They are certainly not visible by eye or binoculars; this is telescope territory! Instead try this…

The Universe at Large

Thinking about size always reminds me that what most humans consider vast is mind-numbingly tiny in the grand view. I came across a video that puts it into some perspective. Using the 400,000 galaxies that have been recorded in the Sloan Digital Sky Survey, you can now get a visual experience that at least begins to scratch the surface of just how vast the Universe is. These galaxies are placed correctly relative to each other.

Remember, these light blobs you’re seeing are galaxies like our own – albeit generally smaller, since ours is on the large side, and each one is a collection of billions of stars. There are only 400,000 galaxies represented, and the total number is approximately 100 billion individual galaxies. So what you see in the video would have to be multiplied by 25 million more to be a true image. The total stars probably figure around 70 sextillion stars or 70,000,000,000,000,000,000,000. Let’s take a peek