Category Archives: Astrophysics

The “Super Blood Blue Moon” is just a lunar eclipse

In the last few days I’ve already answered some few emails and questions in social media about the Super Blood Blue Moon happening on the night from 31st January to 1st February 2018. What is this? Is this really important?

Short answer: No, it is not! This is just a lunar eclipse. The rest is hype to sell the story.

Visions of a Total Lunar Eclipse within clouds - 8 October 2014 - Sydney

Visions of a Total Lunar Eclipse within clouds – 8 October 2014 – Sydney. More information and high resolution images in my Flickr. Credit: Ángel R. López-Sánchez.

Long answer: Let me use an email I wrote yesterday replying the questions asked by a journalist about this astronomical event.

1. Can you please define “super moon” “blood moon” and “blue” moon as they occur individually?

—> Supermoon: this is a term that many astronomers (me included) don’t like, as it was introduced by an astrologer (not an astronomer) but it is now very popular. It is just the moment the full moon is happening near the perigee (the Moon in its closest point to Earth). But, that is the important thing, the difference in size of a “supermoon” with respect an average moon is that a supermoon is ~5-6% larger than the average moon. That is almost nothing!!! Many people are confused with the “14% difference” between the supermoon and the micromoon (when the moon is near the apogee, the farthest point to the Earth).

I insist: it is VERY difficult for our naked eye to distinguish a supermoon from an “average” moon.

You can read a lot about this in the post I wrote two years ago and also in the second episode entitled “Blueberry Moon” of the new science podcast “The Skyentists” produced by Kirsten Banks and me.

—> Blood moon: If we astronomers don’t like the term “supermoon”, we really hate the name of “blood moon”. This is just a lunar eclipse!!

—> Blue moon: the now “standard” definition of a blue moon is when a second full moon is happening within the same calendar month. That is, it was full moon on Jan 2nd, the second full moon this month in Jan 31st is a blue moon.

HOWEVER, strictly talking THIS IS NOT TRUE FOR EASTERN AUSTRALIA (NSW, Tasmania, Victoria) and New Zealand, as the moment of the full moon is actually at 00:26am Feb 1st (Sydney/Melbourne time). It is true for Queensland (at 11:26pm Jan 31st), Alice Spring (at 10:56pm Jan 31st) and Perth (9:56pm Jan 31st).

In any case, the ONLY IMPORTANT real astronomical event is that this is a lunar eclipse (the rest is added to create some hype).

You can get plenty of information about the lunar eclipse in this webpage in and also in this PDF file from NASA Lunar Eclipses.

All the important information for the lunar eclipse happening on the 31st Jan 2018. Credit: F. Espenak / NASA. Here the PDF file.

Australian astronomers have also written about this lunar eclipse. I recommend to have a look to this nice article published by Tanya Hill in The Conversation and also this article by Alan Duffy in Australia’s Science Channel

2. Is this the first time a super blue blood moon has occurred in 150 years?

Probably not, I don’t know, we actually don’t care about this much… It is just a lunar eclipse!!!!

3. How significant is this lunar event?

As I said, it is just a lunar eclipse. That is the point. The rest is added.

4. We are in north-west Victoria. What can people expect to see?

It does not matter where you are in Australia (or in the world, as long as it is night) to see this event. The only differences will be the local weather conditions… if the weather is good, you’ll see a very nice lunar eclipse. It is a perfect opportunity to enjoy the sky!!

5. Are there any tips to getting the best view of the eclipse, or what would be the best times to see it?

The best moment to see the eclipse is when the moon is completely covered by the Earth’s shadow. This happens between 11:52pm and 1:08pm, with the maximum eclipse at 12:30am. You’ll see a red-orange moon in the sky, pretty spectacular.

Addendum 31st Jan: I’ve been using the hashtag #itisjustalunareclipse in social media to say that, at the end… it is just a lunar eclipse!


31 January 2018 — Total Lunar Eclipse in
PDF file with all info of the lunar eclipse from NASA Lunar Eclipses.
Supermoons, post published in this blog, 11 Nov 2016
A blue blood supermoon is coming, by Alan Duffy in Australia’s Science Channel, 24 Jan 2018
The next Full Moon brings a lunar eclipse, but is it a Super Blood Blue Moon as well? That depends…, Tanya Hill in The Conversation, 29 Jan 2018.
A beginner’s guide to the Moon, Ian Musgrave and Genelle Weule in ABC News, 31 Jan 2018.
The “Trifecta” Lunar Eclipse on January 31st, great article by Kelly Beatty in Sky & Telescope, 29 Jan 2018.


The first detection of an electromagnetic counterpart to a gravitational wave event

Full AAO Media Release, published at 01:00am Sydney time, 17 October 2017, that I coordinated.

For the first time, astronomers have observed the afterglow of an event that was also detected in gravitational waves. The object, dubbed AT2017gfo, was a pair of in-spiralling neutron stars in a galaxy 130 million light years away. The death spiral was detected in gravitational waves, and the resulting explosion was followed by over 50 observatories world wide, including the AAO and other observatories here in Australia.

On August 17, the Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO), based in the United States, detected a new gravitational wave event, called GW170817.

GW170817 is the fifth source of gravitational waves ever recorded. The first one was discovered in September 2015, for which three founding members of the LIGO collaboration were awarded the 2017 Nobel Prize in Physics.

The GW170817 data are consistent with the merging of two neutron stars and are unlike the four previous events, which were merging black holes.

Artist’s illustration of two merging neutron stars. The narrow beams represent the gamma-ray burst while the rippling space-time grid indicates the gravitational waves that characterize the merger. Swirling clouds of material ejected from the merging stars are a possible source of the light that was seen at lower energies. Credit: National Science Foundation/LIGO/Sonoma State University/A. Simonnet.

The Advanced-Virgo interferometer, based in Italy, was online at the time of the discovery and contributed to the localization of the new gravitational wave burst.

Based on information from LIGO and VIRGO, numerous telescopes immediately sprang into action to determine if an electromagnetic counterpart to the gravitational waves could be detected.

Meanwhile, NASA’s Fermi satellite independently reported a short burst of gamma-rays within 2 seconds of the merger event associated with GW170817, consistent with the area of sky from which LIGO and VIRGO detected their gravitational waves.

This gamma-ray detection at the same time and place triggered even greater interest from the astronomical community and resulted in more intense follow up observations in optical, infrared and radio wavelengths.

A team of scientists within the Dark Energy Survey (DES) collaboration, which includes researchers from the Australian Astronomical Observatory and other Australian institutions, working with astronomers at the Harvard-Smithsonian Center for Astrophysics (CfA) in the U.S., were among the first astronomers to observe the electromagnetic counterpart of GW170817 in optical wavelengths.

Using the 570-megapixel Dark Energy Camera (DECam) mounted at the 4m Blanco Telescope at Cerro Tololo Inter-American Observatory in Chile, DES identified the kilonova AT2017gfo in the nearby galaxy NGC 4993, located only 130 million light years from us, as the optical counterpart of GW170817.

Composite of detection images, including the discovery z image taken on August 18th and the g and r images taken 1 day later. Right: The same area two weeks later. Credit: Soares-Santos et al. and DES Collaboration.

“Because of its large field of view, the Dark Energy Camera was able to search almost the entire region where LIGO/VIRGO expected the gravitational wave source to be, and its exquisite sensitivity allowed us to make detailed measurements of the kilonova – the extremely energetic outburst created by the merging neutron stars,” AAO Instrument Scientist and DES Collaboration member Dr Kyler Kuehn stated.

A kilonova is similar to a supernova in some aspects, but it is different in others. It occurs when two neutron stars crash into each other. These events are thought to be the mechanism by which many of the elements heavier than iron, such as gold, are formed.

“But as impressive as it is, the Dark Energy Camera is only one of many instruments with a front row seat to this celestial spectacle. A lot of effort has gone into preparing dozens of telescopes around the world to search for electromagnetic counterparts to gravitational waves”, Dr Kuehn added.

Simultaneously to the DES study, a large group of Australian astronomers obtained follow up observations of the kilonova AT2017gfo at optical, infrared and radio wavelengths, using 14 Australian telescopes as part of the ARC Centre of Excellence for Gravitational Wave Discovery (OzGrav) and other Australian programs.

Their data are consistent with the expected outburst and subsequent merger of two neutron stars, in agreement with the results derived for GW170817 by the LIGO/Virgo collaboration.

“Before this event, it was like we were sitting in an IMAX theatre with blindfolds on. The gravitational wave detectors let us ‘hear’ the movies of black hole collisions, but we couldn’t see anything. This event lifted the blindfolds and, wow, what an amazing show!!”, A/Professor Jeff Cooke, astronomer at Swinburne University who led many of the observations said.

The Australia team also conducted observations at the 3.9m Anglo-Australian Telescope (AAT), that is managed by the Australian Astronomical Observatory (AAO). Additional archive data from the 6dF survey obtained at the AAO’s 1.2m UK Schmidt Telescope were also used.

“The observations undertaken at the AAT place important constraints on the nature of the environment in which the kilonova occurred”, AAO astronomer Dr Chris Lidman said.

The follow up observations were not scheduled, but the excitement that this event generated in the astronomical community was so large that regular programs were placed on hold.

“Many astronomers dropped any other planned observation and used all the available resources to study this rare event”, said PhD candidate Igor Andreoni (Swinburne University and Australian Astronomical Observatory), first author of the scientific paper that will be published in the science journal “Publications of the Astronomical Society of Australia” (PASA).

The study also reveals that the host galaxy has not experienced significant star-formation during the last billion years. However, there is some evidence that indicates that NGC 4993 experienced a collision with a smaller galaxy not long time ago.

The position of the kilonova AT2017gfo, found in the external parts of NGC 4993, may suggest that the binary neutron star could have been part of the smaller galaxy.

Australian astronomers were thrilled to contribute to both the detection and the ongoing observations of the kilonova AT2017gfo, the electromagnetic counterpart to the gravitational wave event GW170817.

“We have been waiting and preparing for an event like this, but didn’t think it would happen so soon and in a galaxy that is so near to us. Once we were alerted of the gravitational wave detection, we immediately contacted a dozen telescopes and joined the worldwide effort to study this historic event. It didn’t let us down!”, A/Professor Jeff Cooke said.

“It was crucial to have telescopes placed in every continent, including Australia, to keep this rare event continuously monitored”, PhD candidate Igor Andreoni said.

“To me, this gravitational + electromagnetic wave combined detection is even more important than the initial detection that resulted in the Nobel Prize. This has changed the way the entire astronomical community operates”, AAO Instrument Scientist Dr Kyler Kuehn stated.

The first identification of the electromagnetic counterpart to a gravitational wave event is a milestone in the history of modern Astronomy, and opens a new era of multi-messenger astronomy.

More information:

AAO Media Release

AAO Media Release in Spanish / Nota de prensa del AAO en español

LIGO Media Release

DES Media Release

OzGrav Media Release

ESO Media Release

NASA Media Release

Article in The Conversation: “After the alert: radio ‘eyes’ hunt the source of the gravitational waves”, by Tara Murphy and David Kaplan

Article in The Conversation: “At last, we’ve found gravitational waves from a collapsing pair of neutron stars”, by David Blair

Multimedia, videos and animations:

Although there are many videos around there talking about this huge announcement, I particularly like this one by Derek Muller (Veritasium):

Historic ESO-Australia agreement

This is BIG. Australian astronomers have tried for almost 2 decades to be part of the European Southern Observatory (ESO). Yesterday, 11th July 2017, at a ceremony happening during the Annual Meeting of the Astronomical Society of Australia (ASA) in Canberra, Australia, ESO’s Director General, Tim de Zeeuw, and the Australian Minister for Industry, Innovation and Science, Arthur Sinodinos, signed a 10 years Strategic Partnership between Australia and ESO.

Image composition showing all the ESO observatories and the Headquarters. Credit: ESO/M. Kornmesser.

Following the ESO-Australia Strategic Agreement, Australian astronomers (including me!) will have access to telescope time at La Silla and Paranal Observatories in Chile. The ESO-Australia Strategic Agreement also provides crucial opportunities for Australian influence and technical and scientific input, stimulating international research and industry collaborations.

This is particularly important for the Australian Astronomical Observatory (AAO), as we are developing key instrumentation for ESO (as the ESOP positioner for the VISTA telescope), and that was a key part of the deal, with new opportunities to develop further telescope instrumentation in the nearby future. That also means an important re-arrangement within the AAO, which details are still unknown, but in which we’ll give our best.

At a ceremony in Canberra, Australia, on 11 July 2017, an arrangement was signed to begin a ten-year strategic partnership between ESO and Australia. The partnership will further strengthen ESO’s programme, both scientifically and technically, and will give Australian astronomers and industry access to the La Silla Paranal Observatory. It may also be the first step towards Australia becoming an ESO Member State.
This picture shows all the signatories of the arrangement. From left to right: Virginia Kilborn, President of the Astronomical Society of Australia, Warrick Couch, Director of the Australian Astronomical Observatory, Sue Weston, Deputy Secretary, Department of Industry, Innovation and Science, Senator the Hon Arthur Sinodinos, Minister for Industry, Innovation and Science, Tim de Zeeuw, ESO Director General, Brian Schmidt, Vice Chancellor of the Australian National University, Laura Comendador, Head of the ESO Cabinet and Patrick Geeraert, ESO Director of Administration. Credit: Australian Government.

The Australian Government will invest $129 million over 10 years in the partnership, including the $26.1 million already announced for 2017-2018 Australian Budget. This may also be the first step towards Australia becoming an ESO Member State.

Exciting times await!

More details:

Mysterious Tabby’s Star dims again: observations needed

Let’s face it: KIC 8462852 (also Tabby’s Star or Boyajian’s Star) is a weird star. Since its unusual light variations were discovered by citizen scientists using data of NASA’s Kepler space telescope in September 2015 many, many things have been written by professional and amateur astronomers, science communicators and “searchers of mysteries”, as an interesting hypothesis about its behavior was that it could be signs of activity associated with intelligent extraterrestrial life constructing a Dyson swarm. Of course, this just run wild in general media, and many astronomers since them have been asked by journalist to talk about “Mysterious Tabby’s Star”.

In particular, this theme soon captured the attention of some of my friends at the Instituto de Astrofísica de Canarias (IAC, Spain), as they weekly produce an amazing ~2h science communication podcast Coffee Break: Señal y Ruido (Signal to noise). I’m proud to participate in this podcast from time to time, remotely from Sydney. Coffee Break: Señal y Ruido is, at the moment, one of the most important science communication podcasts in Spanish, with tens of thousands of listeners every week, and broadcasted weekly in several radio stations in Spain and South America.

Well, as the “core” of Coffee Break: Señal y Ruido are IAC astronomers, they decided to submit an observing proposal to get time to obtain spectroscopic data of Tabby’s star using the 1.2m Mercator Telescope, located at the Roque de los Muchachos Observatory (La Palma, Canary Island, Spain). The proposal is led by Marian Martínez González, with Héctor Socas-Navarro, Andrés Asensio, Carlos Westendorp and Carlos González in the team. They got time last week, and were observing till last Wednesday night. They did a great job in social media (please follow @pcoffeebreak) under the hashtag “CB_Tabby“, explaining how observations are conducted in professional telescopes and the results they were obtaining on the fly.

On Sunday night, observations were already showing “something weird” happening again in Tabby’s star. These features were detected by spectroscopy, no photometry. They contacted the very same Tabetha S. Boyajian (Tabby), the initial study’s lead author, who is leading an international follow-up of the star. She sent this message to her collaborators alerting of the weird behavior in Tabby’s star:

And indeed follow-up observations continued during the week. Last night, Friday 19th May 2017, the alert of confirmed by other telescopes: Tabby’s star had dimmed 3%!! This is the plot obtained by The Las Cumbres Observatory Global Telescope (LCOGT) network:

Plot showing the relative brightness of Tabby’s star with time, obtained by Las Cumbres Observatory Global Telescope network. The lowest point shows a 2% drop.

This LCOGT plot shows the brightness of Tabby’s star relative to the star’s normal brightness: the lowest point shows a 2% drop! Tabetha S. Boyajian (Tabby) triggered the alert:

Many media, including Sky and Telescope, New Scientist and Popular Science, have included the news in the last few hours, that is also running wild in social media. But none of these are saying that the actual alert comes from the observations lead by Marian Martínez González (IAC) and “Coffee Breakers” at the 1.2m Mercator Telescope at the beginning of the week! I really think this is not fair, and proper credit to the team that actually triggered the alert at the beginning of the week must be given.

Now, professional astronomers are triggering the “targets of opportunity” to observe Tabby’s star with small and big telescopes. But amateur astronomers are also invited to contribute too!

Star KIC 8462852 in infrared (2MASS survey) and ultraviolet (GALEX). Credit: Infrared: IPAC/NASA, Ultraviolet: STScI (NASA). File from Wikipedia:

KIC 8462852 or Tabby’s Star is a 11.7 magnitude star visible with telescopes larger than 5 inches (130 mm) in a dark sky. It is located in the constellation Cygnus (hence, it is visible for all the Northern hemisphere and part of the South hemisphere, although a bit too low for latitudes below 20 degrees south). If you have an equipment that allows to get accurate photometry using several broad-band filters and are interested on contributing to real scientific observations, please don’t hesitate: try to observe KIC 8462852 these days.

Successful BBC and ABC Stargazing Live TV events at Siding Spring Observatory

Article originally written by Ángel R. López-Sánchez for the “AAO Observer” 132, August 2017. Credits of all the photos: Ángel R. López-Sánchez.

Colorful lights in dome of our Anglo-Australian Telescope in preparation for the Stargazing Live TV shows.

During two weeks in late March and early April 2017, famous physicist and TV presenter Professor Brian Cox co-hosted two “Stargazing TV” shows emitted live from Siding Spring Observatory in the BBC and in the ABC. The stage of these major TV events was our Anglo-Australian Telescope, (AAT) at Siding Spring Observatory, on the edge of the Warrumbungle National Park near Coonabarabran, NSW.

BBC Stargazing Live shows at Siding Spring Observatory were emitted on the early morning of Wednesday 29th, Thursday 30th and Friday 31st March 2017 (evenings of the previous days in the UK). BBC Stargazing Live TV shows were hosted by Professor Brian Cox and TV presenter and comedian Dara Ó Briain, with the participation of biologist and BBC presenter Liz Bonnin and Broome-based amateur astronomer Greg Quicke (who was very popular in social media, receiving the nickname of #SpaceGandalf).

During BBC Stargazing Live astrophysicist and science communicator Lisa Harvey-Smith (CSIRO) was also interviewed. Astronomer and journalist Chris Lintott (Oxford University) was in charge of reporting the news of the citizen science project “The Search for Planet 9“, led by astronomers at the Australian National University and launched in the first episode of BBC Stargazing Live. This citizen science project uses images taken with the Skymapper telescope at Siding Spring Observatory to search for a new planet in our Solar System.

#StargazingABC live episodes were emitted the following week (Tuesday 4th, Wednesday 5th and Thursday 6th April 2017). Hosts Professor Brian Cox and TV presenter Julia Zemiro were joined by astronomers to inspire Australia to explore our Universe and tackle astronomy’s most intriguing questions. Astronomer Lisa Harvey-Smith (CSIRO) also participated as TV presenter for the #StargazingABC shows.

AAO’s Fred Watson, Steve Lee and David Malin were interviewed several times during the ABC and BBC Stargazing Live shows.

SAMI observers at the Anglo-Australian Telescope shared the dome with ABC crew while preparing instrument and telescope for observations on the afternoon of Sunday 2nd April.

For #StargazingABC first episode, the Milky Way, AAO astronomers Ángel López-Sánchez and Steve Lee prepared a new astronomical color image using data taken with the CACTI auxiliary camera of the AAT, which was broadcasted in the episode. This image shows Diffuse gas and dust in the heart of the Carina Nebula. The bright star is Eta Carinae, a massive double star at the end of its live that will soon explode as a supernova. The “Keyhole” is the dark cloud in the centre of the image.

Both Stargazing Live ABC events were very successful. #StargazingABC live episodes reached 2.7 million viewers across metro and regional Australia. They also had a huge impact in social media. ABC 1st TV episode reached over 240K people and had more than 8K reactions in Facebook, comments and shares, similar numbers to those obtained with ABC TV’s New Year’s Eve Family Fireworks stream. Regarding Twitter, the #StargazingABC hashtag reached 18.4 million users and produced 16.8K tweets from 6.3K unique contributors. 12.8K of these tweets were produced during the broadcasts, making #StargazingABC trend no.1 in Australia.

Credits of all the photos: Ángel R. López-Sánchez.

More information: AAO news: ABC Stargazing Live at the AAT.


Eta Carinae and the Keyhole Nebula

Eta Carinae and the Keyhole Nebula

Diffuse gas and dust in the heart of the Carina Nebula. The bright star is Eta Carinae, a massive double star at the end of its live that will soon explode as a supernova. The “Keyhole” is the dark cloud in the centre of the image.

Image obtained as part of the “ABC Stargazing Live” events at Siding Spring Observatory (NSW, Australia), 4 – 6 April 2017.

Data taken on 3rd April 2017 using the CACTI camera in 2dF at the 3.9m Anglo-Australian Telescope. Color image using B (12 x 60s, blue) + [O III] (12 x 60 s, green) + Hα (12 x 60 s, red) filters.

More sizes and high-resolution image in my Flickr.

Credit: Ángel R. López-Sánchez (Australian Astronomical Observatory and Macquarie University), Steve Lee, Robert Patterson & Robert Dean (AAO), Night assistant at the AAT: Wiston Campbell (AAO).


Milky Way rising, LMC, and AAT

Milky Way rising, LMC & AAT

Milky Way, Large Magellanic Cloud, and Anglo-Australian Telescope. Combination of. 6  frames, each of 30 seconds, CANON EOS 5D Mark III, 16mm, f/2.8, ISO 1600. Thursday 2 March 2017. The dome was illuminated in one of the frames by a car leaving the building.

More sizes and high-resolution image in my Flickr.

Credit: Ángel R. López-Sánchez (AAO/MQU).