Mars is the 4th planet from Sun, and the place that holds our imagination because of the possibility that there might be life there. There are some similarities to Earth, like its day length, solid ground and polar caps, but there are many differences as well, like its much smaller size, mass and gravity. And don't forget about the extremely cold temperatures. Let's learn about Mars compared to Earth.

After its disaster last year, Orbital ATK is ready to visit the International Space station again with its Cygnus resupply ship. Its next launch is set for Sunday at 4:44 PM EST. Here's more information on the launch, and how you can watch it live.

This week's Carnival of Space is hosted by Brian Wang at his Next Big Future blog.

The New Horizons spacecraft is already 209,437,000 km (130,138,000 miles) past Pluto (as of Dec. 4, 2015), making it 5,226,950,000 km (3,247,880,000 miles) from Earth. So, yes, it's way out there. Recently, it took the closest images ever of a distant Kuiper Belt object, setting a record by a factor of at least 15, according to NASA. The team says this image demonstrates the spacecraft's ability to observe numerous similar bodies over the next several years.

There is more to the Earth than what we can see on the surface. In fact, if you were able to hold the Earth in your hand and slice it in half, you'd see that it has multiple layers. But of course, the interior of our world continues to hold some mysteries for us. Even as we intrepidly explore other worlds and deploy satellites into orbit, the inner recesses of our planet remains off limit from us.

The Zodiac once played an important role in humanity's cosmological beliefs. Today, they are no longer accurate and regarded as an old superstition.