Blog from December, 2010

Today is the longest day of the year in the Southern Hemisphere, also called the Summer Solstice. The word solstice comes from the Latin "sol" - "Sun" and "sistere" - "to stand still" and it's the time of the year when the position of the Sun (in the sky) reaches it's Northernmost extreme. It's the time of the year when we get the most daylight. Of course we cannot and we MUST NOT LOOK AT THE SUN in the sky WITHOUT PROTECTION. But like the ancient people, we can observe it without problems at sunrise and at sunset.

If we use the same observation point (like our deck for instance) we could make a note of the place where the Sun rises every day. Ok, maybe not every day but once a week. We will see that as the season changes, the Sun will also change it's rising and setting point sideways, little by little, along the horizon. It will do that until it will reach the northernmost point and then it will start going back, journeying towards the southernmost point - just like a pendulum. It's been doing this for about 4.5 billion years but of course we only started to notice it only about 11,000 years ago.

Here is a great collage taken by Anthony Ayiomamitis in Greece. He took one picture of sunrise at the Winter Solstice, one at the Equinox and one at the Summer Solstice. You can see there is a significant change in the position where the Sun rises, depending on the season.

Image credit Anthony Ayiomamitis

At Solstice, the Sun appears to rise from the same spot and it takes a few days until it becomes obvious that it started it's journey back (along the horizon). This is the reason that Christmas is celebrated a few days later (and not on the day of the solstice) because it took ancient people a few days to be able to tell that the longest night of the year was gone. They were able to do that by observing the place where the Sun was rising and setting.

So how would the Solstice look like on Mars?
Well, it would look like this: 

We know it because Spirit acquired this view of the Martian sunset from Gusev Crater on April 23, 2005. Using data from images such as this, scientists have learned that twilight on Mars is longer than on Earth, lasting for up to two hours before sunrise or after sunset. Dust high in the atmosphere scatters light to the night side of the planet. Similar twilights are seen on Earth following major volcanic eruptions.
Image Credit:NASA/JPL-Caltech/Cornell/Texas A&M

Of course, the real question is:

"How would it feel to watch the Sun rising above the Martian horizon, at solstice, from the deck of your Martian bach?"

To this question, a group of scientists and space enthusiasts led by Dr. Robert Zubrin (see the book "The Case for Mars") is trying to answer from here, from Earth. They are inspiring us to dream that one day, humankind will be there on Mars to admire the Solstice sunrise. Or sunset. Or just admire the courage and dedication backed up by science that made us take off to the stars.

Doctor Zubrin and the Mars Society setup a Mars Analogue Research Station here on Earth in the Utah Desert, and they give the chance each year to selected crews to experiment and study towards human colonisation of Mars. Here is what they have to say about this experience:

"The Mars Society has identified three prime goals to be met by the Mars Analog Research Station Project:

  • The Stations will serve as an effective testbed for field operations studies in preparation for human missions to Mars specifically. They will help develop and allow tests of key habitat design features, field exploration strategies, tools, technologies, and crew selection protocols, that will enable and help optimize the productive exploration of Mars by humans. In order to achieve this, each Station must be a realistic and adaptable habitat.
  • The Stations will serve as useful field research facilities at selected Mars analog sites on Earth, ones that will help further our understanding of the geology, biology, and environmental conditions on the Earth and on Mars. In order to achieve this, each Station must provide safe shelter and be an effective field laboratory.
  • The Stations will generate public support for sending humans to Mars. They will inform and inspire audiences around the world. As the Mars Society's flagship program, the MARS project that will serve as the foundation of a series of bold steps that will pave the way to the eventual human exploration of Mars.

Mars Analog Research Stations will be operated by Mars Society researchers and will be made available to NASA and selected scientists, engineers and other professionals from a variety of institutions worldwide to support science investigations and exploration research at Mars analog sites.
Indeed, with so much at stake, Mars is a test for us. It asks us if we intend to continue to be a society of pioneers, people who dare great things to open untrodden paths for the future. It puts us to the question of whether we will be people whose deeds are celebrated in newspapers, or in museums; whether we will continue to open new possibilities for our descendants, or whether we will become less than those who took on the unknown to give everything we have to us. Mars is the great challenge of our time."

Looking forward to seeing you from there!
Clear Skies,

Haritina

This year, on 21st of December 2010, the Moon will rise in eclipse as visible from New Zealand. The total phase of this eclipse lasts for just over 72 minutes, with the partial umbral eclipse spanning almost 3.5 hours.

In northern parts of New Zealand to just south of Auckland, moonrise occurs just before the onset of totality, so all parts of the total stage of the eclipse are visible. Further south only the later parts of the total phase will be visible. More than half of the total eclipse is visible in all of the North Island and the top half of the South Island. At Timaru the Moon rises about 1 minute before the time of mid eclipse. Further south only the final stages of totality are visible; at Invercargill moonrise is just over 15 minutes before the end of the total part of the eclipse.

Some times of moon rise in New Zealand are:
N. Is. Auckland 8.35pm, Hastings 8.35pm, New Plymouth 8.45pm, Wellington 8.49pm.
S. Is. Nelson 8.56pm, Christchurch 9.07pm, Dunedin 9.25pm, Invercargill 9.36pm.

This is a poor eclipse for the southern hemisphere. It occurs with the Moon at is greatest northerly declination so at its lowest in southern skies and its occurs on the shortest night of the year.

All stages of the total eclipse of the Moon are visible from North America and the eastern Pacific. South America will see the earlier stages up to totality. On the other side of the Pacific, the start of the eclipse is before Moon rise in New Zealand.

Eclipses always fascinated people and observing them made people understand the Earth is round.

We have eclipses because the Earth gets in the way in between the Moon and the Sun.

Here is a great kiwi page on how the Moon looks like if photographed during a total eclipse http://www.possumobservatory.co.nz/astrogas/sky002-lunar_eclipse-2007-photos.htm, by one of New Zealand's leading astrophotographers, John Drummond, the Director of the Astrophotography Section of the Royal Astronomical Society of New Zealand.

Lunar eclipses can only occur at full Moon. They don't happen every time we have a full Moon because the plane in which the Moon orbits the Earth is tilted five degrees to the plane that the Earth orbits the Sun (also called the Ecliptic). There is a periodicity in the eclipses timing and this is called the Saros cycle. Many ancient civilisations (for instance the Babylonians) built sanctuaries that respected the Saros cycle (18 years). In short, all the factors that make an eclipse happen now will repeat (with surprising accuracy!) exactly one Saros cycle from now and another eclipse (of very similar geometry) will happen then. This Saros cycle is the very powerful predictive tool that the Babylonians were so clever to discover.

The Chinese word for eclipse is chih, which means “to eat.”

We always use capital letter when we talk about our Moon (The Moon) to differentiate it from other natural satellites that other planets have, also called moons.

Clear skies for Tuesday night!

(Data about the eclipse timing and visibility throughout New Zealand was taken from the Royal Astronomical Society of New Zealand Website - www.rasnz.org.nz)

Photo of the final phase of the total lunar eclipse from 28 August 2007, photo credit John Drummond.