Moon Jupiter Conjunction Sept 29th 2009 (click for larger image)

Lovely close conjunction (appulse, for some) of the Moon and planet Jupiter tonight.

The Moon appears to be about half a degree in diameter to us on Earth, so tonight, Jupiter is about half degree from the Moon.

I have just captured the image on the right from the UK, with my Canon dSLR camera, using its 18-55 mm standard lens.

If you are in the United States for example, this view of the Moon and Jupiter conjunction is coming towards you NOW!

So I suggest you get outside tonight, and take a look!

It’s rare to be able to see the Solar System’s giant planet Jupiter, so close to our Moon.

You’ll also notice the waxing gibbous Moon (as it’s called). This means it’s getting close to full.. the full “Harvest Moon” will be seen on Sunday October 4th.

So, best of luck.

Post a comment here, if you also manage to observe this wonderful spectacle tonight.

It’s been designated  ”Spring Moonwatch” week, as part of the IYA 2009 and we have been blessed with wonderful clear skies here in South-East England. 

I have helped run two public events at my local astro society . I even gave a talk yesterday to about 30 people, about the Moonwatch week and what to see on the Moon.  And it used my own Moon images, taken over the last couple of weeks.

Two or three of the newcomers, became obviously enthused with the idea of Moon observing, which made it feel very worthwhile.

Newtonian 6 inch reflector on EQ6 mount, observing the 9-day Moon

Tonight, I snapped the 9 day old Moon.

To the right, is my old 6 inch reflector, which I bought on eBay in 2003.  

Originally, it was on a simple alt-azimuth mount, but I have recently added new tube rings and dovetail bar, enabling it to be put on the Skywatcher EQ6 mount. (Vastly more stable and of course, driven)

It has worked really well this week for capturing images of the Moon, as it has progressed from 3-day crescent through to 9-day Moon, tonight.

(I shall put together a montage of images from this week.)

Using my now trusty, Canon 1000D dslr, I have (as always) been very pleased with  the results.

Here is an image of the 9+ day Moon, I took tonight.

9+ Day Old Moon, 2009/04/04 (click for larger)

We are familiar with occultations of the Sun and the Moon. We give these occultations a special name – eclipses – solar eclipse for the Sun and lunar eclipse for the Moon.

Lunar Eclipses

A lunar eclipse occurs when the Earth, Sun and Moon are aligned, with the Earth between the Sun and the Moon.

The Earth is three times larger in diameter than the Moon, so it easily blocks out the Sun’s light and casts a shadow on the Moon.

The Moon of course, does not produce light itself, only reflecting sunlight, so it looks dark during an eclipse.

In fact the degree of darkness does vary due to the condition of Earth’s atmosphere. If Earth’s atmosphere is clean, it will bend sunlight to some extent and this gives the Moon a slight illumination.

If however Earth’s atmosphere is dusty, as happens after major volcanic eruptions, it does not bend sunlight so much and a lunar eclipse can be a very dark one.

As the Moon orbits around the Earth once every month approximately, you might expect there to be a lunar eclipse each month, but this does not happen.

The reason is that the orbit of the Moon is inclined a few degrees to the orbit of the Earth. This ensures the Moon does not pass into the Earth’s shadow every month.

However, lunar eclipses are more often seen than solar eclipses because when they do occur, they can be seen from everywhere on Earth where the Moon can be seen at that time.

When a solar eclipses takes place, it can only be seen from a narrow strip of places on Earth. The path of totality tracks across the Earth’s surface, with a strip of partial totality on either side.

Solar Eclipses

WARNING… Never, ever look at the Sun through binoculars or a telescope, as you will certainly damage your sight. Observe an eclipse only by projecting the Sun’s image onto a sheet of card.

Solar eclipses happen when the Moon is aligned between the Sun and Earth, so that sunlight is blocked-out and a shadow is cast on the Earth.

This gives a remarkable effect here on Earth, as the Sun is obscured and then reappears some minutes later.

From a particular point on Earth, a solar eclipse is sometimes partial, and occasionally total, meaning that the Sun is completely covered by the Moon.

During a total eclipse, the Moon just about exactly covers the Sun. This is remarkable in itself.

The Moon covers the Sun in this way because the ratio of their diameters, happens to be very similar to the ratio of their distances from the Earth.

Putting it another way, the Sun and Moon have roughly the same angular size in the Earth’s sky.

This exact coverage gives rise to wonderful effects at the edge of the Sun during total eclipses such as the “diamond ring” and the “string of beads”.

It has also enabled astronomers to study phenomena very close to the Sun’s surface, such as solar prominences and the Sun’s corona.

Other Occultations

Occultations of other objects in the sky are always keenly observed and have been important to astronomers in the past.

Lunar occultations are when the Moon passes in front of a star or planet and this is interesting to observe. The Moon has no atmosphere, so stars suddenly disappear without any fading and then later, suddenly come back.

Double stars have been discovered through observing lunar occultations.

Sometimes, an star will “graze” the edge of the Moon, revealing details of hills and mountains on the Moon, as the star disappears and then reappears several times.

As recently as 1977, faint rings were discovered around the planet Uranus because a star flickered as it was occulted by Uranus.

It is thought that the Moon was probably once part of the Earth, until some cataclysmic event broke it off.

Now the Moon and the Earth rotate about about their common centre of gravity. This point of rotation is actually within the Earth, because the Earth is so much more massive, but it is nearer the surface than the centre.

Crescent Moon

The Moon is about one third the diameter of the Earth and it orbits around it every 27.3 Earth days. This is called its “sidereal period”.

However, this is not the same as the time between each New Moon, which is over 29 days, because of the Earth’s rotation about the Sun.

In the time it has taken the Moon to go once around the Earth, the Earth has covered approximately one twelveth of its orbit around the Sun. So the Moon has to “catch-up”, so to speak, one twelveth of its orbit around the Earth (just over 2 days), in order to reach the same Sun-Moon-Earth relative alignment for the New Moon to appear.

Most people will be aware of the “far side” of the Moon which we never see from Earth. This is because the Moon rotates on its axis with the same period that it orbits around Earth. Consequently, it always presents the same side towards the Earth.

The far side is not actually the “dark side” of the Moon – it is actually illuminated by the Sun, but we cannot see it.

The Moon has no atmosphere and its surface has been hit by many objects over time, resulting in its heavily cratered condition.

Seen from Earth, there are obvious light and dark areas. In the past, before telescopes were developed, these were thought to be seas (or Mare from Latin). We now know there is no water on the Moon and these “seas” are just relatively smooth areas of the surface.

Apollo 11 Tranquility Base

This was of course, confirmed when the Apollo 11 space mission landed in one of them (Mare Tranquilitatis or Sea of Tranquility).

Further Apollo landing missions followed, but the Moon remains the only space body that humans have set foot upon.

The Moon is an excellent object to observe with binoculars or a small telescope. It is often bright and easy to see.

Looking through a telescope, you can see the craters and ridges so clearly, that it is possible to imagine you are actually there, flying over the surface and looking down!

Some people think full-Moon must be best for astronomy, but this is just not so. Near to full-Moon, the Sun does not cast shadows on the lunar surface, meaning that you cannot see much detail.

The best time to observe is around half-Moon. With this degree of illumination there is plenty to see, the relief features are defined by shadow and it is not too bright.