Category: Solar System

Lunar Libration

We only see one side of the moon due to the tidal locking of the Moon to Earth. However, we get to see a little more than half the moon. Due to lunar libration we see about 59% of the Moons surface. This libration is due to the dynamics between the Earth and Moon.

The video shows a simulation of one phase cycle of the Moon.

Lunar libration video

How Big is the Earth?

In actual terms the Earth has a diameter of 12 742km and is 40 075km around the equator. That may sound large but in the scheme of the solar system it is it not that big. In the terms of the universe it is totally insignificant. This video compares the size of the objects in our solar system and to other stars.


Ever wanted to take your own photos of the night sky but never knew how. This video gives a very brief explaination of what is involved to get started in this exciting hobby. Just be aware that there is a huge difference in skill level from where he starts (ie a camera on a tripod) to where he finishes. It is very easy to use a camera on a tripod. It takes a lot more determination and money to take good photos like the ones towards the end of this video.

This video is a short documentary on the Collisional Ejection Theory for the creating on the Earth’s moon. It features Bill Hartmann and Robin Canup who were important figures in the development of this theory.

September Equinox 2010

Today every point on Earth has a day and night of very nearly 12 hours for each. This is called an equinox and since this one occurs in September every year it is called the September Equinox. It is also called the Autumnal Equinox in the northern hemisphere as it marks the onset of Autumn.

Only one other equinox occurs every year and it occurs in March. Obviously this is called the March equinox. It is also referred to as the Vernal Equinox and in the northern hemisphere marks the start of spring.

Equinoxes occur when the tilt of the Earth’s of rotation is at a right angle to the line connection the Earth and Sun. This can only occur twice in a single orbit of the Earth around the Sun (ie one year). At the time of each equinox the Sun lies at the intersection of the plane containing the Earth and Sun and the plane defining the Earth’s Equator.

In the figure on the right the blue plane is defined by the Earth’s equator. The yellow plane is the plane containing the earth and Sun (the line the Sun appears to follow is called the ecliptic). The position of the Sun at an equinox is marked as Autumnal and Vernal Equinoxes on the figure. Today the Sun is at the pointed marked as Autumnal Equinox.

Planet X – Nibiru Hoax

This video deals with the Hibiru Hoax. This hoax relates to a planet which is approaching Earth and will cause a major extintion event at some point. Original dates for this has already past. The latest manifestation of the hoax is that the planet will cause havoc on Earth in 2012. This date coincides with yet another doomsday predicted event in 2012 with the end of the current Mayan calendar.

Don’t be fooled by this hoax. There are two explanations that the hoaxers claim is the reason why proof for Nibiru is non-existent. The first is that every profession and armature is somehow in a conspiracy to keep its presence a secret. The other is that it is on the other side of the Sun. The first reason doesn’t even warrant a reply. I can’t explain why it is that we did not see Nibiru when we where on the same side of the Sun as the planet 6 months ago.

This is an image of the Earth and Moon from a distance of 138 million kilometers (114 million miles) by the MESSENGER spacecraft. They are located in the bottom left of the photograph.


Io’s Surface: Under Construction

Jupiter’s moon Io is the most geologically active body in the solar system. All the colouring visible in this image is the result of eruptions on this small moon. The colour is due to the presence of sulfur compounds.

It is thought that there could be as many as 300 active volcanoes on Io. It is estimated that these volcanoes eject enough material to cover the moons surface to a depth of 1 metre every century.

Prior to the flyby of Voyager 1 in 1979 it was thought that this moon would be a dead body with ancient cratering. We now know that Jupiter’s gravity has a great influence on Io. As the moon orbits it is slightly influenced by the planets other moons which does not allow the moon to become tidally looked with the planet. As a result the planet is subjected to tidal forces that cause heating in the moon’s interior. This drives the volcanism observed on Io.

Source: Astronomy Picture of the Day

The 3rd of August marked the 5th anniversary of the lunch of the rocket carrying the MESSENGER spacecraft. In the first 5 years the craft travelled 5.6 billion kilometres (3.5 billion miles). Its ultimate aim is to enter orbit around the planet Mercury. By the time it has entered orbit around the planet it would have passed Earth once, Venus twice and mercury three times. The aim of these flybys is to slow the craft to allow its insertion into an orbit around Mercury.

The main aim of the Messenger mission is to unlock the secrets of Mercury. The craft will examine the planet’s surface and magnetic field. By doing this we may discover the reason(s) for the planets high density, it geological history, the structure within the planet, the nature of its magnetic field and what the detected materials at the planet’s poles are.

The three flybys that have occurred already have provided some tantalising details.

The spacecraft is due to go into orbit around Mercury on the 18th of March of next year. For more information about the Messenger mission check the MESSENGER website. The video gives an over-view of the mission.

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