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.

Anyway.. what I’ve realised is I need more focal length on the telescope, for the imaging of planets.

I put my old 6 inch Newtonian reflector onto the EQ6 mount, then added the Canon dSLR camera.

Ancient 6 inch Newtonian reflector, plus EQ6 telescope mount

It produced this image below, nicely showing three moons of Jupiter.. but no detail on the planet. The clouds must take a lot of the blame, but I see also, I need more focal length.

Jupiter And Moons (Io, Ganymede, Callisto)

The DSLR Canon camera is working at prime focus – using the telescope as its lens and nothing else.. (no eyepiece, or barlow lens etc).

Consequently, to get more magnification and fill the image field of view with the planet, I need a telescope with a longer focal length. My 6 inch (150 mm) reflector has a focal length of only about 700 mm.

(And as a PS. .  what would Galileo have given for an image of Jupiter and its moons, like this?)

So, any suggestions for a good telescope to observe the planets?

Prior to this and going back to ancient times, only the five planets which can be seen with the unaided eye (Mercury, Venus, Mars, Jupiter and Saturn) were known.

Uranus is another “Gas Giant” and much larger than Earth, although it is smaller than Jupiter and Saturn. Uranus is about 31,000 miles in diameter at the equator, but less at the poles due to rotational flattening.

Uranus orbits around the Sun, once every 84 Earth years.

It rotates about its axis, once every 17 hours.

The axis of Uranus is uniquely (for a planet in the Solar System) tilted over at the extreme angle of 82 degrees to its orbital plane. This means that from Earth, we sometimes see a polar region and other times an equatorial region.

On Uranus, the axial tilt means that each polar area is dark for 42 Earth years, and then light for 42 Earth years!

We do not know why the axis of Uranus is tilted so much. Some people think it was the result of a huge collision, long ago.

Observing Uranus from Earth reveals no detail on the planet’s disk, even with a large telescope. It does however look blue-green in colour, due to frozen methane in the atmosphere.

Uranus’ five largest satellite moons can be seen from Earth. These are called Miranda, Ariel, Umbriel, Titania and Oberon. All are smaller than our Moon. Titania is the largest.

Uranus ring system (from Voyager)

A remarkable discovery was made in 1977, from Earth. During observation of Uranus occulting (passing in front of) a star, faint rings around the planet were suspected but not confirmed.

Then came the Voyager space probe of 1986 and the rings were clearly seen by it, as it flew past. There are 11 rings in total and they are very thin, probably less than one mile thick.

Voyager also took some remarkable images of Uranus’ satellite moons, especially Miranda which has a strange varied surface.

Uranus has a total of 21 known satellite moons.

Outside SOAS

I travelled to London on the train, to attend the quarterly meeting of the SPA.

These meetings are always held at SOAS (School of Oriental and African Studies), which is part of London University and located just off the splendid Russell Square in Bloomsbury.

In the morning, there was the SPA Council meeting, but at 2pm the main interest of the day began – the quarterly members’ (and their guests) meeting.

There were a number of entertaining and informative talks, but the highlight was Professor Derek Ward-Thompson from Cardiff University.  

He presented on the formation of Stars and Planets, using recent long wavelength (radio) evidence.

In Front Of SOAS - With SPA Vice President Taking A Photo

I left the meeting with the strong impression, the human race is beginning to understand our ancient origins.  

Quite astonishing.

Come to the next SPA meeting – I recommend it.

In August 2008, NASA confirmed water on the planet Mars.

They have analysed Martian soil samples gathered by the Pheonix lander, from the surface of Mars.

How is this done from so far away, you may wonder?

Astonishingly, Pheonix has a robotic arm. It is able to reach out and scoop red soil from the Martian surface, into the spacecraft’s body. There, the soil is heated and the vapours analysed.

Water has been confirmed. It has been suspected for centuries, but only now “touched and tasted” in the words of the scientists involved.

The question of water on Mars, became a full-blown controversy in the late 1800′s.

Leading astronomers notably Percival Lowell, claimed to have observed networks of “canals”, through telescopes. Previously, they had been suggested by Shiaparelli and termed “canali”.

Quickly, it was speculated they were the work of intelligent beings – hence the notion of “Life on Mars”. Water is a prerequisite for life as we know it.

In 1898, the publication of H G Wells’ famous novel “The War of the Worlds”, added populist fuel to the debate.

Perhaps this latest discovery from NASA of water evidence, will rekindle the speculation? I’m sure, further work is needed for any proof.

Neptune is the furthest out of the “Gas Giant” planets and is right out at the limits of our Solar System, 2800 million miles from the Sun.

The story of its discovery is fascinating…

Neptune

Neptune’s existence was suspected long before it was actually discovered.

Astronomers in the early 1800′s found that they could not reconcile the observed position of the newly discovered planet Uranus, with the position they expected through calculations.

So some astronomers began to suggest that perhaps there was an undiscovered planet in the same area of the Solar System, that was affecting the orbit of Uranus.

Various people became involved in the search for the new planet. Notably, these included a young French mathematician called Urbain Le Verrier and a young English mathematician called John Couch Adams.

Both of these men calculated where in the sky, they would expect Neptune to be found. Adams did not publish his work, but Le Verrier did by means of two notes, in 1845 and 1846.

The search to find Neptune observationally began.

John Challis, Professor of Astronomy at Cambridge, used the Northumberland 11.6 inch refractor but did not find it.

(Incidentally, this telescope can be visited and is still used at the present time, in Cambridge. I have seen it and it is a wonderful piece of astronomy history)

Reviewing the episode later, after the new planet had been discovered, Challis found that he had actually seen and recorded Neptune almost immediately in the predicted position, but he had not realised it. I bet he was cross!

Meanwhile, Le Verrier had sent his calculations and predictions to Johann Galle at the Berlin Observatory.

With this valuable information, Galle looked and found very quickly. Neptune was discovered on his first night’s observation in 1846.

Later, it was discovered that Adams had also been correct with his predictions of Neptune’s position, but unfortunately, it had just taken too long for the English astronomers to follow it through to the observation stage.

Neptune is not actually that difficult to see with a telescope, if you know where to look and what you are looking for.

Through a telescope, the Neptune’s disk looks blue. Like Uranus, this is due to light absorption by methane.

Neptune is also very similar in size to Uranus.

The largest of Neptune’s moons, Triton was discovered soon after the planet itself in 1849, but the second moon, Nereid, took much longer (1949). It is close to the planet and hard to see.

The most significant recent event was the Voyager space mission. It flew past Neptune in 1989.

Voyager found six additional satellite moons, together with a faint ring system – another similarity with Uranus.

However Neptune does not share Uranus’ extreme axial tilt. Neptune’s axis is inclined at just 29 degrees to the plane of the orbit. Only a few degrees more tilted than Earth.

Voyager also succeeded in measuring the period of rotation. Neptune’s “day” was found to be 16 hours 7 minutes long.

Saturn Rings Close Up

Saturn is another “Gas Giant” like Jupiter, although not quite as big.

Nevertheless, Saturn is the second largest planet in the Solar System and is huge compared to Earth.

It has a diameter of around 75,000 miles at the equator (less at the poles, due to its rotation) and is over 700 times greater in volume than Earth.

But like Jupiter, it has a lower density than Earth. Saturn would actually float in water!

Saturn’s orbit is twice as far from the Sun as Jupiter, being 887 million miles away, and it takes over 29 Earth years to make one revolution.

Saturn spins quickly on its axis, each Saturn day lasting just 10 hours.

Observing Saturn

Observationally, Saturn is the “wow” object of the Solar System, because of its rings. The rings are easy to see with a modest telescope and must have got many people interested in astronomy. They certainly did it for me!

Saturn’s globe is not nearly so interesting to look at, although it does show some banding, but this is far less marked than that of Jupiter.

The early telescope astronomers, notably Galileo, could not see Saturn’s rings at all clearly. Galileo was confused by what he saw as Saturn’s strange elongated shape.

Saturn’s Rings

Sometimes (about every 13 or 15 years – it alternates), the rings are seen “edge-on” from Earth and almost disappear from our view. This may have been part of Galileo’s problem.

Other times, the rings are seen more “face-on” and it is then possible to see detail in the ring system, including the famous “Cassini Division”, a dark gap between the “A” and “B” rings.

We now know from space probes, that there are actually many thousands of small rings and they are composed of rocks, ice, fine particles and dust.

All this orbiting material is kept in place by the gravitational effects of Saturn’s various satellite moons, including small “shepherd” moons that actually orbit within the ring system.

Space Probes

Visits to Saturn by space probes began with Pioneer in 1979.

Then came the Voyager pair in 1980 and 1981.

These provided close-up images, but the most astonishing images have come recently (2004/5) from the Cassini-Huygens probe. This actually landed on Titan, Saturn’s largest moon.

Saturn’s Moons

Saturn has many satellite moons (over 30) but there are five big ones.

As just mentioned, Titan is the biggest moon and it can be seen with a small telescope. It is actually larger than our Moon, but unlike it, Titan has an atmosphere.

The other largish moons of Saturn (over 600 miles diameter) are Rhea, Iapetus, Dione and Tethys.

Smaller moons of Saturn include Mimas, Enceladus and Hyperion.

This figure is very much an average because interestingly, Mercury has a notably elliptical orbit. Its distance from the Sun varies from about 28 million miles at the closest, to about 43 million miles at furthest away.

Mercury

The proximity to the Sun has always made Mercury difficult to observe from Earth. You can never see it against a dark sky background. It is only visible for a few minutes before sunrise or after sunset.

Even when at the most favourable, it still appears close to the Sun in our sky. And in fact, astronomers had little information on the details of Mercury until the Mariner spacecraft photographed it in the mid-1970′s.

Another unusual aspect to the planet is that it rotates on its axis very slowly, taking nearly 59 Earth days to turn once. So the length of a Mercury day is 59 Earth days.

Mercury takes 88 Earth days to complete an orbit of the Sun, so there are less than two days in a year on Mercury! In fact there is almost an exact 3:2 relationship – 3 days every 2 years.

Cratered Mercury with volcanos (Messenger)

However, from the viewpoint of a fixed point on Mercury’s surface, the Sun would rise in the sky only once every 176 Earth days or once every 2 Mercury years.

The axis of Mercury is not tilted like the Earth, so there would be no seasonal effect.

The surface of Mercury is hard and rocky. There is little atmosphere and it suffers extremes of temperature between -180C and +470C.

All in all, Mercury is a very inhospitable place, by our standards.

Venus is the second closest planet to the Sun. It is 67 million miles from the Sun.

Venus’ orbit is almost circular as the eccentricity of the ellipse is very small. Each orbit takes 225 Earth days.

Venus rotates on its axis only slowly, taking 243 Earth days. So strangely, a Venus day is longer than a Venus year.

Like Mercury, the other planet that is closer to the Sun than Earth, Venus is hot and inhospitable. Although in other respects, Venus is quite different.

Venus is covered by a dense, swirling, opaque atmosphere of Carbon Dioxide. This produces a major “greenhouse effect” and makes Venus very hot.

Venus is hotter than Mercury, with a surface temperature of about 500C, even though it is twice as far from than the Sun.

Sometimes Venus is referred to as Earth’s sister planet, because they are of very similar size. But as we have just seen, surface conditions are very different.

Because its orbit is closer to the Sun the Earth’s, Venus always appears in the same area of the sky as the Sun, but unlike Mercury it is much easier to observe.

Indeed, Venus is often a brilliant object in the sky, partly because its dense atmosphere reflects to much light.

Through a telescope though, it is rather disappointing. The cloudy atmosphere prevents us seeing any surface features.

Venus does exhibit phases though. Because of its position relative to the Earth and Sun, its face is sometimes fully illuminated, sometimes only partly.

The phases were first observed by Galileo in 1610. Venus is new when closest to us. It is full, when furthest away.

Transits of Venus, when the planet passes across the face of the Sun from our viewpoint here on Earth, are very interesting to watch.

Transits occur in pairs separated by eight years, about every 120 years.

The last transit of Venus was in 2004. I personally, got a splendid view of it by projecting the Sun’s image onto a sheet of paper.

There will be another transit in 2012.

There have been several space missions to Venus. Some have moved down through the cloud layers and tried to investigate the surface.

Most of our knowledge of the planet’s surface has come from radar mapping by the Magellan probe in the early 1990′s.

This surface mapping revealed a fascinating volcanic world with many craters. There is a huge plain and two main areas of highlands called Ishtar Terra in the north and Aprodite Terra around the equator.

There are also mountains – one is higher than Everest here on Earth.

Consequently, astronomers usually measure space distances in light years.

One light year is the distance light travels in one year.

Light travels pretty fast – 186,000 miles per second (and according to the theory of relativity, nothing, but nothing, can travel any faster).

A light year therefore works out to be 6 million million miles.

So let us take an imaginary journey from the Sun, riding on a beam of light that has just been created from the nuclear reactions of the Sun

Our light-beam transporter leaves the Sun and heads out into the Solar System.

Let look at how it takes us to get to objects, even when travelling a the speed of light. This may give us some sense of some of the vastness of Space.

We set off from the Sun (and let us assume that all the planets are in a line)… NOW!

After 3 minutes we pass Mercury and after another 3 minutes, we speed past Venus.

It takes 9 minutes in total to reach the Earth, even at the speed of light (so we actually “see” the Sun as it was 9 minutes ago)

Just 1 second later, we pass the Moon.

Then we are heading towards Mars, and reach it 4 minutes later. We have now travelled a total of 142 million miles since we set-off from the Sun.

At 45 minutes into our journey, we reach Jupiter. Gosh! Isn’t it big and red?

Saturn is nearly twice as far from the Sun as Jupiter. On our light beam takes 80 minutes in total to reach it. We fly past Saturn and it also looks big, although not quite as big as Jupiter was.

We continue, on out into the far reaches of our Solar System.

Uranus goes past at 3 hours of travel.

Followed by Neptune at over 4 hours

We might catch a glimpse of Pluto (now no longer thought of as a planet) at around 6 hours, although Pluto has an eccentric orbit and is sometimes inside Neptune’s orbit.

That is the end of our Solar System. We are now heading out into deep space on our light beam.

It is would be sensible to get some sleep now. It is going to take over four YEARS to reach the nearest star!

The nearest star is the alpha Centauri binary star plus its companion, at around 4.3 light years, in the constellation of Centaur.

The brightest star we see from Earth is Sirius in the constellation of Canis Major. It would take us nearly nine years to reach Sirius, even travelling at the speed of light.

So when we look at Sirius from Earth, we see it not as it is now, but as it was, nearly 9 years ago.

Other bright stars we see from Earth are further away. Vega in the constellation of Lyra is 26 light years away, whereas Rigel in Orion is 800 light years distant.

Even at the great distance of Rigel, we are still with in our own galaxy, the Milky Way.

We believe that our galaxy the Milky Way, has a diameter of 100,000 light years.

The nearest galaxy outside our own, is the Andromeda nebula. This can be seen from Earth with the unaided eye, as a fuzzy blob in the constellation of Andromeda. It is the most distant object with can see without a telescope and it is 2.5 million light years away.

So even at the speed of light, it would take us 2.5 million years to reach the nearest galaxy. From Earth, we see the Andromeda galaxy as it was 2.5 million years ago, not as it is now.

It could actually have disappeared for all we know!

Yet to us on Earth, it would look as though it was still there, for the next 2.5 million years.

Other galaxies (and there are countless) are much further for the Earth and could take hundreds or thousands of million years to reach.

Space is big!