Pluto’s status as a planet has once again been called into question after the head of Nasa said he believed the celestial body to be a planet.
Speaking at the FIRST Robotics event in Oklahoma, Nasa administrator Jim Bridenstine went against convention by placing himself firmly on one side of the Pluto debate.
“Just so you know, in my view Pluto is a planet,” he said. “You can write that the Nasa administrator declared Pluto a planet once again. I’m sticking by that, it’s the way I learned it and I’m committed to it.”
Pluto was first declared a planet in 1930 after it was discovered by American astronomer Clyde Tombaugh. At the time it was believed to be the ninth planet from the Sun, existing on the outer edges of the solar system in the Kuiper belt.
Its status as a planet was called into question 62 years later after other similarly-sized objects were discovered in the same region of space.
1/30 Striking Africa
“The striking colour and texture of Africa Illizi, Algeria”
2/30 Favourite Reef
“Every day spent living in space is a great day, but today was particularly special. I got to speak with one of my inspirational heroes Prof Stephen Hawking and his amazing daughter Lucy, who developed the Principia Space Diary to engage children with STEM subjects. As well as talking about dark matter, quantum entanglement, alien life and light beam powered nanocraft we also got to see an amazing pass over the Bahamas and this – my favourite reef smile emoticon”
3/30 Russia’s north-east coast
“Sunrise approaching Russia’s frozen north-east coast”
4/30 Hello London
“Hello London! Fancy a run? 🙂 #LondonMarathon”
5/30 Bahamas
“50 shades of blue: Bahamas”
6/30 Yinchuan
“Snow on the mountains next to Yinchuan in China”
7/30 Rocket flames in Africa
“Is it just me or do I see some rocket flames down there? These strange land features are in the Erg Iguidi desert, with its yellow stripes of sand stretching from Algeria to northern Mauritania in the Sahara”
8/30 Stunning colours
“Sunlight reflecting the stunning colours of this Himalayan lake”
9/30 The real Everest
“The real thing: found Everest! Last picture turned out to be third-tallest mountain Kanchengjunga”
10/30 Go Exomars
“Go #Exomars – have a great mission. Earth has more in common with Mars than you might think… #AfricaArt”
11/30 Tenerife
“Amazingly clear view of Tenerife”
12/30 Midday winter sun
“Some midday winter sun glinting off Greenland’s snow-capped peaks”
13/30 Sand dunes
“Great texture in these huge sand dunes, Saudi Arabia”
14/30 Dragon Dam
“The dam makes this river look like a dragon’s tail. Oahe Dam north of Pierre, South Dakota in the United States. (North is to the right)”
15/30 Smoking volcano
“Spotted volcano smoking away on Russia’s far east coast this morning – heat has melted snow around top”
16/30 New Zealand
“New Zealand looking stunning in the sunshine. Mt Cook centre left with the Grand Plateau to the front and Mt Tasman (3,497m) to the right of the Grand Plateau. Fox Glacier in the middle then Franz Josef curving right. Tasman Lake (largest at front) is at the foot of the Tasman glacier which runs along the front of them. The Hooker Glacier flows out behind Mt Cook coming down to meet the Mueller Glacier on the left of the photo. The Murchison Glacier is at the front of the photo running parallel with the Tasman Glacier”
17/30 Plankton bloom
“Another great pass over Patagonia and a swirling plankton bloom off the coast”
18/30 Alaska
“We don’t often get such clear views of Alaska”
19/30 Lights along the Nile
“Lights along the Nile stretching into the distance from Cairo”
20/30 Kamchatka
“The Pacific ‘Ring of Fire’ clear to see amongst the volcanoes of Kamchatka, Russia”
21/30 Cumulonimbus
“I’m guessing there was an impressive storm going on under that cumulonimbus cloud”
22/30 Night Sahara
“Night-time Sahara – you can really see how thin the Earth’s atmosphere is in this picture”
23/30 Japan
“Tokyo and Japanese coast. This image shows most of Japan with the largest mass of light corresponding to Tokyo. The white lights on the left are fishing boats”
24/30 Morning sun volcanoes
“Morning sun striking active volcanoes in Guatemala”
25/30 Tapajos River
“The vast waters of the Tapajos river, Amazonia”
26/30 Patagonia
“Beautiful glacial river water flowing from this Patagonian ice field Lake Viedma, West is up”
27/30 Dubai Palms
“Minus the #Dragon photobomb this time…”
28/30 Sediment in Ethiopia
“Sediment spilling into this mountain lake, Ethiopia”
29/30 Italy
“We have phases of ‘short nights’ on the International Space Station – sunlight is nearly always visible right now. No prizes for guessing where this is…”
30/30 Panama Canal
“From one mighty ocean to another – ships passing through the Panama canal”
1/30 Striking Africa
“The striking colour and texture of Africa Illizi, Algeria”
2/30 Favourite Reef
“Every day spent living in space is a great day, but today was particularly special. I got to speak with one of my inspirational heroes Prof Stephen Hawking and his amazing daughter Lucy, who developed the Principia Space Diary to engage children with STEM subjects. As well as talking about dark matter, quantum entanglement, alien life and light beam powered nanocraft we also got to see an amazing pass over the Bahamas and this – my favourite reef smile emoticon”
3/30 Russia’s north-east coast
“Sunrise approaching Russia’s frozen north-east coast”
4/30 Hello London
“Hello London! Fancy a run? 🙂 #LondonMarathon”
5/30 Bahamas
“50 shades of blue: Bahamas”
6/30 Yinchuan
“Snow on the mountains next to Yinchuan in China”
7/30 Rocket flames in Africa
“Is it just me or do I see some rocket flames down there? These strange land features are in the Erg Iguidi desert, with its yellow stripes of sand stretching from Algeria to northern Mauritania in the Sahara”
8/30 Stunning colours
“Sunlight reflecting the stunning colours of this Himalayan lake”
9/30 The real Everest
“The real thing: found Everest! Last picture turned out to be third-tallest mountain Kanchengjunga”
10/30 Go Exomars
“Go #Exomars – have a great mission. Earth has more in common with Mars than you might think… #AfricaArt”
11/30 Tenerife
“Amazingly clear view of Tenerife”
12/30 Midday winter sun
“Some midday winter sun glinting off Greenland’s snow-capped peaks”
13/30 Sand dunes
“Great texture in these huge sand dunes, Saudi Arabia”
14/30 Dragon Dam
“The dam makes this river look like a dragon’s tail. Oahe Dam north of Pierre, South Dakota in the United States. (North is to the right)”
15/30 Smoking volcano
“Spotted volcano smoking away on Russia’s far east coast this morning – heat has melted snow around top”
16/30 New Zealand
“New Zealand looking stunning in the sunshine. Mt Cook centre left with the Grand Plateau to the front and Mt Tasman (3,497m) to the right of the Grand Plateau. Fox Glacier in the middle then Franz Josef curving right. Tasman Lake (largest at front) is at the foot of the Tasman glacier which runs along the front of them. The Hooker Glacier flows out behind Mt Cook coming down to meet the Mueller Glacier on the left of the photo. The Murchison Glacier is at the front of the photo running parallel with the Tasman Glacier”
17/30 Plankton bloom
“Another great pass over Patagonia and a swirling plankton bloom off the coast”
18/30 Alaska
“We don’t often get such clear views of Alaska”
19/30 Lights along the Nile
“Lights along the Nile stretching into the distance from Cairo”
20/30 Kamchatka
“The Pacific ‘Ring of Fire’ clear to see amongst the volcanoes of Kamchatka, Russia”
21/30 Cumulonimbus
“I’m guessing there was an impressive storm going on under that cumulonimbus cloud”
22/30 Night Sahara
“Night-time Sahara – you can really see how thin the Earth’s atmosphere is in this picture”
23/30 Japan
“Tokyo and Japanese coast. This image shows most of Japan with the largest mass of light corresponding to Tokyo. The white lights on the left are fishing boats”
24/30 Morning sun volcanoes
“Morning sun striking active volcanoes in Guatemala”
25/30 Tapajos River
“The vast waters of the Tapajos river, Amazonia”
26/30 Patagonia
“Beautiful glacial river water flowing from this Patagonian ice field Lake Viedma, West is up”
27/30 Dubai Palms
“Minus the #Dragon photobomb this time…”
28/30 Sediment in Ethiopia
“Sediment spilling into this mountain lake, Ethiopia”
29/30 Italy
“We have phases of ‘short nights’ on the International Space Station – sunlight is nearly always visible right now. No prizes for guessing where this is…”
30/30 Panama Canal
“From one mighty ocean to another – ships passing through the Panama canal”
In 2005, astronomers discovered a dwarf planet called Eris that was 27 per cent larger than Pluto. A year later, the International Astronomical Union laid out its official definition for what constituted a planet. Pluto was not included.
Since then it has been classified as a dwarf planet, though the icy object has attracted a dedicated following of people who claim Pluto should be considered a planet.
In 2015 Nasa’s New Horizons mission to Pluto made several major discoveries that added fuel to the debate.
Alan Stern, the Nasa scientist who led the New Horizons mission, subsequently co-authored a paper calling for Pluto to be reclassified.
The Society for the Preservation of Pluto as a Planet has campaigned for Pluto’s status to be upgraded.
“For over 75 years school children all over the world have learned that our solar system has nine planets,” the group’s website states.
“Pluto’s status as a planet has sparked the human imagination for decades… Now is not the time to downgrade Pluto’s status.”
