Why haven’t we seen the other side of the moon?

Answer by Award-Winning Scifi Author C Stuart Hardwick

The far side of the moon was first photographed by Luna 3 in 1959. The above is a recent image captured by NASA’s LRO.

If you are asking why we can only see the near side from Earth, that’s because the moon tidally locked. It used to spin faster than it orbits, but just as its gravity causes a tidal bulge in Earth, our gravity causes a bulge in the moon.

Tidal bulges are carried along by the rotation of the body in question, and so create a slight gravitational imbalance. Today, this imbalance is pushing the moon away as a rate of 3.5 cm per year and slowing Earth’s rotation by about a millisecond per century. In the past, that same process slowed the moon’s rotation until it’s rotational and orbital periods became the same.

Now the moon’s stuck with it’s tidal bulge facing us. Any perturbation that would tend to turn the moon with respect to Earth gets cancelled out by the pull of our gravity on the moon’s bulge, and nothing is ever likely to disturb it enough to break free.

Will the moon be closer to Earth one day and will it make ocean tides more severe?

No. The moon is drifting away about 4 centimeters a year. Over time it will drift out to space and Earth will have no moon.

Of course, the sun might become a red giant before that, killing everything, but the answer to your question is no.

As a result the tides will become less severe.

However, as the climate warms and the ocean rises as much as it is now, cities and communities near the sea will become flooded. This has nothing to do with the moon.

It is discovered now that the expansion of the universe is accelerating. Does the source of expansion lie inside or outside of the universe?

We don’t know what is causing the expansion of the universe, only that we can observe that the expansion is accelerating.

We assume there is nothing outside the universe “pulling it” so we attribute the accelerating expansion to an unknown force we presently call “dark” (i.e. unknown) “energy.”

We believe there’s an unknown energy called “dark energy” that causes the universe to expand the way it does.

It leads to all kinds of interesting ideas about the big bang, such as the big bang gradually accelerated exponentially causing another big bang infinitely.atom-630x281

The Black Eye Galaxy from your back yard

Steve Morris is an amateur astronomer and took this picture of the Black Eye Galaxy from his home. This stuff is floating above our heads in plain view. You just need the right equipment to see it and you don’t need Hubble (all of the time).

I copied this from his Facebook post in the Astronomy for Fun group.

Now think about this. You see the stars above you at night. Did you know you can see not only our own Milky Way Galaxy, but other galaxies as well?

You don’t need to depend on NASA for everything. This stuff is right above your head. You just need the right equipment, knowledge and determination to capture pictures like this.

What planets are bigger than Earth?

The four gas giants are larger than Earth: Jupiter, Saturn, Uranus and Neptune.

Venus is slightly smaller, but very nearly the same size as Earth. Mercury and Mars are smaller than Earth.

So there are 4 planets larger than Earth in our solar system, and they are the four gas giants.solar_system_3

Meet ‘Steve,’ a Totally New Kind of Aurora

Canadian citizen scientist photographers spotted a fleeting type of aurora not seen before, dubbed “Steve,” and scientists have started working out what’s causing them.

Steve seen with the Milky Way over Childs Lake, Manitoba.

While the northern and southern lights have dazzled watchers of the night sky for millennia, vigilant citizen scientist photographers found another type of aurora over the past few years: a short-lived shimmering purple ribbon of plasma. Their intriguing discovery drew the attention of space scientists, who have just begun to study them.

“Dedicated aurora chasers, especially from Alberta, Canada, were out in the middle of the night, looking north and taking beautiful photos. Then farther south they happened to see a faint narrow purple arc as well,” says Elizabeth MacDonald, a space physicist at NASA Goddard Space Flight Center in Greenbelt, Maryland. There’s different physics behind those purple aurora, she says.

MacDonald led a team who observed the aurora by sending one of the European Space Agency’s Swarm satellites through it. The results suggest they’re a manifestation of accelerated and heated charged particles coming from the sunthat interact with a particular part of the Earth’s magnetic field in the ionosphere. The team published their findings in Science Advances Wednesday.

The citizen scientists weren’t sure about what they’d seen, so they called the strange aurora structure “Steve.” The name caught on, and MacDonald and her team kept it, proposing the backronym Strong Thermal Emission Velocity Enhancement (STEVE). While scientists had known about lower-latitude currents of charged particles for decades, they had no idea that they could produce auroras visible to the eye. But now that people have smartphones and digital cameras more sensitive than what scientists had back then, they can pick out these rare aurora, which last only about an hour.