Moon and Jupiter gather Friday to celebrate the anniversary of the lunar landing

Friday will mark the 49th anniversary of one of the largest Achievements of humanity: Apollo 11 the first lunar landing. On July 20, 1969, at 10:56 pm Eastern Time, while 600 million people watched television around the world, astronaut Neil Armstrong stepped on the surface of the moon and said, "It's a small step for the man … a giant step for humanity. If you were alive at the time, no doubt you watched or at least listened to the radio coverage of this incredible event.

And if you went out that night and looked up, you would have seen the moon appear as a broad crescent, 35 percent lit by the sun. Almost a dozen degrees to his right, you would have seen a very shiny silvery white object, imitating a star but not flickering – instead, glowing with a steady glow. It would have been the planet Jupiter.

Now, move 49 years to today. On Friday evening (July 20th), baduming your sky is reasonably clear, you can see the same two celestial objects that were so prominent in the night sky almost half a century ago: the moon and the planet Jupiter. [Exploring the Apollo Moon Missions Using Mobile Apps]

About an hour after sunset, the attractive celestial duo will be visible in the southwestern sky, roughly halfway up the horizon to the point at the most high (called the zenith). The moon, which will be just one day after the first phase of the first quarter – 63% lit by the sun – will be located just above Jupiter, at a distance of about 3.5 degrees.

As we noted earlier, your closed fist is about 10 degrees, so the distance between the moon and Jupiter will be about one-third of a hand.

When the moon is in the first quarter phase or just after, as it will be on Friday, we get the best views of the lunar landscape along the sunrise or sunset line. Around these moments when the moon is half-lit or gibbous phase, the features that are close to the terminator stand out clearly. By using a telescope with a small optical power (magnifications of 20 to 40x), or even with good binoculars, we can see a wealth of details on the lunar surface.

In a telescope, Jupiter is also a main attraction, better observed in the early evening. when he is still high and his image is reasonably calm. And his four bright moons are still performing. They look like little stars, though two of them are really bigger than our own moon. You can watch them change their positions to each other from hour to hour and night to night.

In fact, if you look at Jupiter with a small telescope or even binoculars regularly held on Friday night, you'll see at least three and maybe the big four satellites. The number depends on where you are and when you are watching. In the eastern United States, as soon as night falls, you will see two moons flanking Jupiter on either side: Io and Ganymede on one side and Europa and Callisto on the other.

At 23:06. EDT, Ganymede will disappear from sight as she will be overshadowed by Jupiter's shadow. This moon will reappear gradually from 12:52 EDT (9:52 PM Pacific time), again placing the four satellites in view. But an hour later, Europa will disappear for a few hours while she pbades behind the disc of Jupiter

So, on the night of the anniversary of the first lunar landing, while you enjoy the sight of Jupiter near from the moon, keep in mind that up to four other moons are visible with only a slight optical aid.

And is it cloudy that night? Well, me, Apollo-gize.

Joe Rao is an instructor and guest speaker at the Hayden Planetarium in New York. He writes on astronomy for Natural History magazine, the Farmers' Almanac and other publications, and he is also a meteorologist on camera for Verizon FiOS1 News in Lower Hudson Valley of New York . Follow us on @Spacedotcom Facebook and Google+. Original article on Space.com