Moon Perigee and Apogee

Patience pays off. Six months ago I took a picture of the moon at Perigee, the closest point in its orbit to Earth. It was a full moon. Today (28-Nov-2012) it is a full moon again, but the moon is furthest away from Earth in its orbit - Apogee. The moon is indeed smaller, and in the exact ratio of the distances - about 15%. It is an experiment that I have wanted to do for a very long time and I am happy that I've completed it successfully.
The Apogee moon photo is from the moonrise which gives the orange tint to the picture. The reason for the orange moon is detailed in the following article.

Here is a photo of the two moons. It is not a matter of resizing. The same camera, same setting, same zoom were done to both photos. A picture is worth a thousand words.

Moon comparison at Perigee and Apogee

Carnival of space #277

Hi and welcome again to the Venus Transit for another carnival of space. The Transit is history at least for the next hundreds years, but there is plenty of other stuff going around so take a small break and dive into this issue.

Carnival of Space

Ray Sanders from "Dear Astronomer" has a new episode of "The Cosmic Ray Show" airing on November 27th at 7:00PM Pacific. Join Ray along with his co-host, astronomer Jerry Hilburn, and special guest, astronomer Dave Reneke as they discuss the recent solar eclipse, and take a virtual tour of the astronomical sights of the southern hemisphere. Featured musical guest is Google+ sensation, Ryan Van Sickle.

Is there a role for airships in the space age? This post from tranquility base introduces two novel ways that airships can contribute to space exploration. 

Centauri Dreams looks at Rod Hyde's ideas on laser fusion, as developed in a starship paper he wrote in the 1970s along with collaborators at Lawrence Livermore National Laboratory.

Two articles from Next Big Future:
In an interview with NPR, John Grotzinger, the principal investigator for the Mars Curiosity rover mission, indicated that the data [that they are getting from Mars Science Laboratory Sample Analysis at Mars Instruments] is gonna be one for the history books. It's looking really good. The announcement will be in a few weeks after more tests and confirmations are run. Curiosity can not directly detect the presence of Mars life. Curiosity can detect organics, which would be the presence of the building blocks of life on the surface of Mars. 

Information acquired by L2 this week revealed plans for a “game-changing” announcement as early as December that a new commercial space company intends to send commercial astronauts to the moon by 2020. According to the information, the effort is led by a group of high profile individuals from the aerospace industry and backed by some big money and foreign investors. The company intends to use “existing or soon to be existing launch vehicles, spacecraft, upper stages, and technologies” to start their commercial manned lunar campaign. New Space Watch identifies the company Golden Spike as the company that will have the commercial manned mission to the moon. It is registered in Colorado to Alan Stern, a former administrator of NASA's Science Mission Directorate, and now working on the New Horizons Pluto mission at the Southwest Research Institute in Boulder, Colorado.

Universe Today also relates to the new findings on Mars. The Mars Science Laboratory team has hinted that they might have some big news to share soon. But like good scientists, they are waiting until they verify their results before saying anything definitive.
Once again people are worrying that astronomical alignments will cause Eathquakes, Astroblogger analyses why the latest batch is nothing to worry about. If alignments and earthquakes aren't enough, now the largest solar flare recorded (the Carrington Event) is being attributed to a planetary alignment. But it just aint so.

Lucky Astroblogger is an Aussie so he had a great chance to view the last solar eclipse. Lucky for us, he shares his photos with us!

Pamela Hoffman from Everyday Spacer sends two articles: Attend an airshow and Watch a partial Lunar eclipse

And as a last treat watch the latest video from Amy Shira Teitel  author of VintageSpace. I already subscribed to her YouTube channel and eager to see new episodes.

That's all for this issue. Hope you all have long days and clear nights.

What Voyager is doing now

In our last article about Voyager, we discussed Voyager's last photo from space. After taking that photo which was the end of the grand tour, it seemed reasonable to shut down the mission and let the spaceships continue their eternal journey in space. However, since the spaceships' condition was still very good, most of the systems still functioning and their location was the furthest any object had arrived it seemed sensible to find a new mission for Voyager and not let it waste in space.
Every end is a new beginning and the end of the "Grand Tour" was the beginning of VIM - "Voyager Interstellar Mission". You might have heard on the news that Voyager left or is about to leave the solar system. This is not accurate and we need to first determine where the solar system ends. If our criteria for the edge of the solar system is the distance at which the sun gravity has little effect on celestial bodies, Voyager is still in the inner part of the solar system. The influence of the sun gravity reaches to a distance of about 1 light year from the sun, to the end of the Oort cloud.
A definition which is better for our purpose, is the border of the magnetic field of the sun. The sun's magnetic field moves with the sun. As it is illustrated in the diagram below, the magnetic field seems like a bullet advancing with the sun. It travels with and in front of the sun and stretches to a great distance behind it. Charged particles from the sun (a.k.a "Solar wind") travel very fast, they start to slow down when they meet other charged particles coming from space (a.k.a "Space wind"). The area where Voyager 1 is currently traveling is the place where these two "winds" meet ("wind" is used as a metaphor).

Voyager Interstellar Mission. NASA

In this diagram, the inner circle is the Solar system with its 8 planets (as we said before, there are other objects further away which orbit the sun). The Heliosphere, the sun's atmosphere, reaches beyond and behind the sun, and the Heliosheath is the area where Voyager 1 is currently traveling.
The size of the Heliosheath is unknown and it is changing constantly. The scientists hope that Voyager will be able to cross it and reach the area of the bow-shock. Voyager's energy supply (we will deal with this matter in our next article) will last for the next 10-15 years. In order to conserve energy, all unnecessary instruments were shutdown long ago, and only 5 systems are still functioning. These systems include the communication system, the magnetometer and other instruments to measure the speed and direction of charged particles.
What Voyager discovered is that particles from the sun's direction become slower and slower, and particles not from the sun's direction become more and more common (and with greater speed). This means that Voyager is getting nearer to the area where the majority of particles will not be from the sun (and only in that sense, leaving the solar system). So, it is now a race against time, to get as far as possible before all Voyager's energy is used. The current distance of Voyager 1 from the sun is 120 AU (astronomical unit - the distance from the sun to earth - 150,000,000 KM) and its speed is 3.6 AU per year. In 10 years it will reach a distance of 150 AU from the sun, and if it will still function we will learn a lot about the strange conditions at that far place. Voyager 1 is the front lab of humanity and it provides sci-fi enthusiastic some food for thought  about spaceship travels to other stars and planets.

See Voyager exact distance from earth and sun

Previous articles
Voyager - The grand tour
Voyager's last photo

Voyager - The Last Photo

Most people like family photos, and the more participants the merrier. But there is one family that it is particularly hard to photograph together, mainly because the distances between the brothers and sisters of this family can be above 5 billion KM and they will never get any closer. An experienced photographer will distance himself as far as possible and try to get just the right angle to include as many members of the family as possible. The family we are discussing is the solar system with the Sun and the planets. When Voyager finished the grand tour, it was in a great position to catch most of the family members in one photo. The spaceships' cameras were not needed anymore, both spaceships were not expected to observe additional celestial objects, and the decision was to take one last photo before shutting the cameras down forever. You remember that there were two Voyager spaceships, and to take that special photo, Voyager 1 was chosen, simply because it had a better viewing point. Voyager 1 left the ecliptic plane and was high above it, providing a better photography angle than Voyager 2 who was still near the ecliptic.
There were some other obstacles. The sun (the old grandmother of the family) is extremely bright. The planets (brothers and sisters) are dim and far apart from each other, and the moons (grandchildren) are just too small and dim, so the family portrait  is not really a single picture but a mosaic of about 60 photos combined together, taken with different exposure times and filter. The last of the Voyager mosaic is shown below, taken on February 14th 1990.

Voyager I portrait of the solar system. Credit: NASA

OK, I am sure you did not exactly expect this as a family portrait but it is the best possible composition. The grey squares are the individual pictures, as mentioned, more than 60 frames were needed to get all members of the family, but as often happens, someone is still missing. The letters designate the planets (J - Jupiter , E - Earth, V - Venus , S - Saturn, U - Uranus, N - Neptune) and the bright dot is the sun.  Mercury and Mars are missing from the portrait. Mercury was too close to the sun, and Mars could not be found. Pluto which in 1990 was closer to the sun than Neptune and still a distinguished member of the solar system (until it was kicked out to be a dwarf planet) was too dim and was not included in this picture, maybe as a prophecy to its destiny 15 years later.
The picture is in a very high resolution so please click on it to enlarge it. You will see excerpts presenting the planets themselves. It is possible to see some details on Jupiter and a hint of Saturn's rings. Uranus and Neptune seem larger but this is because the long exposure time of 15 seconds which gave them a little smudge. The sunlight is visible in many pictures, and the camera hardly managed to capture planet Earth. The size of our little planet is less than one pixel and the photograph that shows it got its iconic name by no other than Carl Sagan: "The pale blue dot"

The pale blue dot. Credit: NASA

After these photos, the Voyagers' cameras were shut down forever. Cameras need power, and power is a rare resource in a little spaceship, but these photos are part of the heritage that Voyager left us.

Previous Articles in the Voyager's series:
Voyager - The Grand Tour