Tanya

DISPLAYING POSTS BY: Tanya (37)

Tanya

Dr Tanya Hill is the Planetarium’s astronomer. She loves exploring the Universe and it never fails to amaze her. It was the Orion Nebula that led her to astronomy and she’s reached for the stars ever since.

Asteroid zooms by Earth

Author
by Tanya
Publish date
11 February 2013
Comments
Comments (0)

Most of the time we rush through space without giving it a second thought. But every now and again the Universe reminds us that we are not alone.

On Saturday morning, 16 February, Earth will be buzzed by asteroid ‘2012 DA14’. Its closest approach at 6:25am, will bring it 34,000km from Earth. That’s just a little closer than the geosynchronous satellites – a ring of communication and weather satellites that orbit the Earth at 36,000km. Earlier predictions had the asteroid coming even closer, but Earth’s gravity keeps tugging on the asteroid and changing its predicted path, ever so slightly.

Flight path of asteroid 2012 DA14 The path of asteroid 2012 DA14, which approaches Earth from "below" and passes through the ring of geosychronous satellites. The times given are AEDT.
Source: NASA/JPL-Caltech
 

One thing is quite clear – there is no chance the asteroid will collide with Earth and that’s a good thing. At 45 metres across, it’s not particularly small and probably of similar size to the asteroid that exploded over Siberia in 1908. Known as the Tunguska event, it flattened 80 million trees across an area the size of Port Phillip Bay.

Path of asteroid 2012 DA14 from Melbourne The path of asteroid 2012 DA14 across the south-west sky as seen from Melbourne on the morning of Saturday 16 February 2013. The times indicated are in AEDT while the positions with relation to the horizon are calculated for 5:25am.
Source: Melbourne Planetarium
 

Asteroid 2012 DA14 won’t be bright enough for us to see, but experienced observers could catch a glimpse with a small telescope. It will appear in the south-west, just below the Southern Cross – the hard thing will be pin-pointing it while it’s zipping along at 28,000 km/hour.

The rock was discovered almost a year ago by the La Sagra Observatory in southern Spain. It’s one of a handful of observatories that hunt and monitor Near Earth Objects. Each day, about a hundred tons of interplanetary material falls onto Earth – mostly dust from comets or small fragments from asteroid collisions. But once every 100 years, we expect something larger, like 2012 DA14, to appear. It’s nice to know there are people out there looking and making sure our path is clear.

Trees felled by the Tunguska explosion. The Tunguska event was caused by a similar sized asteroid exploding over Siberia in 1908.
Source: the Leonid Kulik Expedition
 

Links:

A Ustream feed of the flyby from a telescope at NASA's Marshall Space Flight Center in Alabama, will be broadcast from 1pm to 4pm, 16 February (AEDT).

Animations and interviews by NASA scientists

Accounts of the Tunguska event from Science at NASA

Space Shuttle Columbia

Author
by Tanya
Publish date
1 February 2013
Comments
Comments (2)

It was 10 years ago today, 1 February 2003, that the Space Shuttle Columbia broke apart on its way back to Earth. The STS-107 crew had spent 16 days in orbit and were just 16 minutes from landing when the accident tragically occurred.

Crew of STS-107 This photograph survived on a roll of unprocessed film recovered from the accident. Bottom row (L to R): Kalpana Chawla, mission specialist; Rick D. Husband, mission commander; Laurel B. Clark, mission specialist, and Ilan Ramon, payload specialist. Top row (L to R): David M. Brown, mission specialist; William C. McCool, pilot, and Michael P. Anderson, payload commander.
Source: NASA
 

On a trip to the USA in 2002, I attended a talk by astronaut and astronomer, John Grunsfeld. He was asked “why fly into space when the risks are so high?” and his reply has always stuck with me. It was pretty much “because it’s the most amazing thing to do.

He went on to explain that while astronauts are fully aware of the risks involved – and they don't take them lightly – they are also certain that the benefits of what they are doing will lead to greater things for our future.

Today we remember the amazing men and women who have believed in the spirit of space exploration. I hope there will always be pioneers just like them, who are willing to push the limits of what’s possible and dream big for all of us.

Links:

Powerhouse Museum: "Sometimes, when we reach for the stars, we fall short..."

Siding Spring Observatory

Author
by Tanya
Publish date
14 January 2013
Comments
Comments (2)

Like other Australian astronomers last night, I was glued to the computer watching as a fire raged across the Warrumbungle National Park in NSW, home to Australia's world-class optical and infrared telescopes at Sliding Spring Observatory. I think the hardest thing was knowing that it's almost 10 years ago to the day, that fires destroyed the Mt Stromlo Observatory in Canberra. Could this really be happening again?

Fire around telescope A truly frightening image, as Australia's largest optical telescope, the Australian Astronomical Telescope (AAT), is engulfed in smoke.
Source: Rural Fire Services
 

Fires around telescope Fires blaze around cottages in front of the AAT. To the top right of the image are the flames that engulfed the lodge.
Source: FTS webcam
 

Fire at astronomer's lodge The glow as the astronomer's lodge is destroyed. Temperatures at the AAT were measured to be over 100 degrees.
Source: FTS webcam
 

Thankfully, lessons were learnt from that event and there is much hope that measures put into place may have saved the dozen or so telescopes on the mountain. We'll have to wait and see as the damage is assessed over the next few days.

The good news is that all 18 staff were evacuated safely. Many telescope domes are still standing, as new images come through this morning. The building which has been destroyed was the lodge which provided accommodation for astronomers during their observing runs. 

Fire around telescope Electronics were not meant to survive such temperatures.
Source: HATSouth webcam
 

Telescope dome after fire The picture I wanted to see today. The AAT dome still stands, but there will be a wait to access how the telescope fared inside.
Source: LCOGT webcam
 

Our thoughts are with the community of Coonabarabran and those who have been affected by the fires, and our thanks go out to fire services for their great efforts. 

If the telescopes had been destroyed it would have been devastating for Australian astronomical research, all but ending our ability to do continue doing optical astronomy here. Hundreds of researchers and students rely on those telescopes. And it would also have affected the Coonabarabran community, many of whom rely on the telescopes for their livelihoods too.

Images of the event, many taken from the webcams that are normally used by astronomers to check sky conditions during their nightly observations, tell the story.

burnt astronomer's lodge building The burnt out remains of the astronomers lodge. I have fond memories of Margaret's delicious chocolate pudding, which I would devour there, before heading up to the telescope for the night's observing run!
Source: Rural Fire Services

Telescope dome after fire The square "dome" on the left houses the ANU's 2.3 metre telescope which stayed a comfortable 20 degrees throughout the fire. The dome to the top right is the new SkyMapper telescope, led by Nobel Laureate Brian Schmidt and built to continue the work of the Great Melbourne Telescope after it was destroyed in the Mt Stromlo fires. Temperatures there peaked at 65 °C.
Source: Rural Fire Services
 

UPDATE: 

The Warrumbungle Shire Council has set up a Warrumbungle Shire Mayor’s Bushfire Appeal with donations being used solely to assist residents affected by the fire. The NSW Rural Fire Service are reporting that some 40 properties and over 110 out-buildings have been confirmed lost as well as a large number of livestock and farm machinery.

 

Links:

Siding Spring after the fires of January 2013 via Observations Blog, Sydney Observatory

Report from The Australian

Astropixie liveblogging the fire: Sunday night and Monday morning

Watching the total solar eclipse

Author
by Tanya
Publish date
14 November 2012
Comments
Comments (0)

I had never seen a total solar eclipse before, and I was very excited to travel to Queensland to watch Australia's first solar eclipse in a decade just before 6AM this morning. 

It was incredible to wander down to the beach at 4AM and see it already packed with eclipse chasers! Thousands of people were at Palm Cove alone, more in surrounding Cairns and Port Douglas, while some headed inland where the weather prospects were better.

People on beach Eclipse chasers on the beach at Palm Cove, Queensland, awaiting the total solar eclipse.
Image: Tanya Hill
Source: Tanya Hill
 

We saw a magnificent sunrise over the water, but minutes later, when the partial eclipse was due to begin, the Sun disappeared behind clouds. It was an anxious wait but half an hour later, the clouds parted and we all donned our eclipse glasses to see a large chunk missing from the Sun.

The totality was perfect. Just beforehand you could tell that the surrounding light was different; it seemed sharp and unnatural. Then the brilliant diamond ring effect lit up the bottom of the sun and the moment had begun.

Total solar eclipse The moment of perfect totality, when the Moon was exactly in front of the Sun.
Image: Tanya Hill
Source: Tanya Hill
 

I was amazed by the colour - we could really see the pink prominences dancing around the Sun. Everyone cheered and just enjoyed the beauty of this natural show. We could see Venus shining bright above the Sun, the wispy corona and the Sun's outer gaseous layer, along with a dazzling bright ring encircling the Moon. It was surprising how long the two minutes lasted. The second diamond ring effect was blinding and spectacular as the Sun began to emerge once again.

The Yolngu of Arnhem Land tell their eclipse story of the sun-woman and moon-man coming together in the sky as husband and wife. It struck me that this is a phenomena that has been seen by so many, across thousands of years. I feel so fortunate to have shared in the experience.

Links:

'Eclipse groupies take shot in the dark,' The Age, 11 November 2012

'Eclipse sheds light on sizzling sun,' The Age, 14 November 2012 

November solar eclipse

Author
by Tanya
Publish date
1 November 2012
Comments
Comments (5)

Coming up on the 14th November we have the chance to see a solar eclipse. From here in Melbourne it will be a partial eclipse, with 52 per cent of the Sun's diameter covered by the Moon. But up in Far North Queensland and the topmost of the Northern Territory, they will be treated to totality, where the Moon will completely block the Sun for just on two minutes.

Partial Solar Eclipse A partial eclipse will be seen from Melbourne on the 14 November 2012.
Source: Museum Victoria
 

The eclipse will occur during the early morning of 14 November, with the Sun still low in the east. Therefore, a good view of the horizon will be needed. The timing for Melbourne is as follows:

Eclipse begins: 7:16am
Mid-eclipse: 8:06am
Eclipse ends: 9:00am

It is important never to look directly at the Sun, even during an eclipse. While the Sun may appear less bright it can still cause long lasting eye damage.

There are safe ways to look at the eclipse – at the Scienceworks shop you can purchase eclipse glasses that will allow you to watch the event, while protecting your eyesight.

You can also create a simple "pinhole" projection. It's as easy as making a small pinhole in a piece of paper or cardboard. Do not look through the hole, but allow the Sun to shine through and project an image onto a second piece of cardboard. Even a blank wall or clear patch of ground can make good surfaces for projection.

Sometimes nature helps out too. If you can see sunlight travelling through the leaves of a tree, you’ve got yourself some ready made pinhole projections. Check the ground and it might be covered with little crescent Sun images. Take a look at this great example on the Astronomy magazine website.

I’ve never seen a Total Solar Eclipse, so I'm heading up to Queensland for my first chance. I've been told that it's quite an eerie experience to have darkness fall while it's still early morning.

If you will also be in the path of totality for this eclipse, then be sure to check out the Eclipse Megamovie Project. Use your smartphone to upload images and videos of the Sun during totality and the Space Sciences Laboratory in California will combine the footage to create the first ultra-high time resolution movie of a solar eclipse.

What I'm most looking forward to is the chance to see the Sun's corona, the bright and tenuous gas that surrounds the Sun. Normally it's invisible, drowned out by the Sun's glare, but being able to see hidden things is something that's always captivated me about astronomy.

Solar Eclipse from 1999. During totality the Sun's diffuse corona and thin pink chromosphere can be seen.
Source: Luc Viatour. www.lucnix.be
 

New exoplanet in our neighbourhood

Author
by Tanya
Publish date
29 October 2012
Comments
Comments (1)

Alpha Centauri is one of my favourite stars and it just got even more interesting. Astronomers from the European Southern Observatory have found a planet orbiting around it.

These days finding another exoplanet, that is a planet that orbits a distant star, isn’t so unusual. We know of over 800 exoplanets and the Kepler spacecraft has spied 2,000 more that are waiting confirmation.

But this one is special because of its star. Here’s why…

Alpha Centauri is lovely and bright, the third brightest star in the night sky, and it is prominent in our southern sky. It is the brighter star of the Two Pointers, which lead us to the Southern Cross.

Southern Cross and Two Pointers Alpha Centauri (yellow star on the far left) and Beta Centauri (blue star to the right of Alpha Centauri) point towards the Southern Cross.
Image: Akira Fujii
Source: Akira Fujii
 

Alpha Centauri is also great to look at through a telescope. What appears as a single bright star in the night sky, becomes two stars when seen through even a modest telescope. Both of the Sun-like stars – Alpha Centauri A and Alpha Centauri B – are quite similar so it looks like you’re seeing double. (A fair distance away there’s a third star too, Alpha Centauri C or Proxima Centauri, a faint red dwarf star).

At just over four light years away (or roughly 40 million million km) Alpha Centauri is the closest star to our Sun. If ever we manage to develop the capability for space travel, this is sure to be the star system we set our sights on.

And now it has a planet! The planet is orbiting Alpha Centauri B and it was hard to find, taking over four years of observations. Many follow up investigations will now begin so as to be absolutely certain.

Artistic impression of planet around Alpha Centauri B Artistic impression of the planet around Alpha Centauri B.
Source: ESO/L. Calcada/Nick Risinger
 

The new found planet has a mass similar to Earth, but takes only 3.2 days to orbit the star. It’s a scorched world, with temperatures soaring over 2000°C.

But finding one planet in this star system is really encouraging and there just might be others. If a planet was found at a more reasonable distance from this Sun-like star, it would be very interesting as far as life is concerned.

Any night sky talk I’ve ever given always includes Alpha Centauri. It’s exciting after all these years to learn something new about it.

About this blog

Updates on what's happening at Melbourne Museum, the Immigration Museum, Scienceworks, the Royal Exhibition Building, and beyond.

Categories