Earth gets first glimpse of Pluto up close

Love note: The presence of a ‘heart’ on the surface of Pluto has delighted millions. © PA

After a nine-year, three billion-mile journey through space, New Horizons is sending high definition images of Pluto back to Nasa. It has reignited a hot debate: is Pluto really a planet?

At 8:52pm at John Hopkins University, Alice Bowman received a long-awaited message. Bowman is the missions operations manager (or ‘mom’) for the New Horizons space mission, and the spacecraft — which is the fastest ever produced and around the size of a baby grand piano — had been silent for several hours while it flew past Pluto and collected as much data as possible. Right on schedule, it sent a message to confirm that it had completed its mission safely. History was made.

Cheers erupted among the scientists. ‘We have a healthy spacecraft,’ reported Bowman, smiling. ‘We always talk about the spacecraft as being a child, maybe a teenager. There was absolutely nothing anybody on the operations team could do, just to trust that we had prepared it well to set off on its journey on its own.’

New Horizons travelled 3bn miles for nine years to reach the ‘planet’ and its five moons, and soared within 7,750 miles of its surface. Most of the data it has collected is yet to be transmitted to Earth, but the results are already astonishing.

Firstly, scientists were surprised to find that it is larger than they thought, at 1,473 miles across — around two-thirds the size of Earth’s moon. The dwarf planet also has a reddish tint to its surface, like Mars, quite opposed to the dark, icy world the scientists had predicted. In fact, it appears to have geological features as diverse as mountains, snow, and a bright enigmatic region in the shape of a heart.

The successful mission to the ‘ninth planet’ is a historic moment for humanity’s space exploration journey. But there is more to come: New Horizons will now continue its journey through the Kuiper Belt, and could continue sending data to Earth for years to come — perhaps until the mid 2030s.

‘The most exciting thing will probably be the thing that no one is expecting,’ predicted one eager scientist.

Dwarf planet

Pluto has enchanted scientists and amateur astronomers ever since it was discovered in 1930. But months after New Horizons launched, Pluto was stripped of its planet status by the IAU. It has not ‘cleared its own orbit’, they argued; it is one of several similarly sized objects in the Kuiper Belt. Pretending that Pluto is special because it was discovered first is not science — it’s sentiment.

But the initial data we have received from New Horizons shows it to be even more fascinating than we had first imagined, counter many, including the scientists involved in the project. We should not deny its status as a planet just because we have discovered others like it. Why not just classify these, like Eris and Makemake, as full planets too? Rather than contracting our cosmic horizons, we should allow them to grow.

You Decide

  1. Should Pluto be re-classified as a planet?
  2. Now that it has reached the outer limits of our solar system, one question is clear: where should Nasa explore next?

Activities

  1. Draw and label a diagram of the solar system.
  2. Write an essay arguing for or against the classification of Pluto as a planet.

Some People Say...

“Mystery creates wonder and wonder is the basis of man’s desire to understand.”

Neil Armstrong

What do you think?

Q & A

When will we know more about Pluto?
Keep your eye on the news, because some of the best images are likely to be released over the next few days. However, New Horizons has such a slow radio signal that it will take 16 months to transmit the data it has just recorded back to Earth, and scientists are sure to be analysing it for even longer.
How is it powered?
Many spacecrafts use solar power, but this would be a dangerous plan for a mission so far from the sun. Instead, New Horizons has a nuclear generator. Rather appropriately, it uses plutonium, a radioactive chemical which was originally named after the planet.
Where is it going next?
Further into the Kuiper belt. There are two potential objects that it could reach with its remaining fuel — scientists will choose one by August this year.

Word Watch

Fastest
New Horizons launched at a velocity of 36,000 mph, the fastest object to leave Earth. It used Jupiter’s gravity to increase its speed by 9,000 mph, cutting its journey to Pluto by three years. As it passed by Pluto, it was travelling at 34,000 mph.
Five moons
Currently, scientists are aware of five moons which orbit Pluto. It is the largest moon, Charon, which is the most significant. Like Pluto, it has far more geological activity than the New Horizons scientists had previously believed.
Kuiper Belt
Containing thousands of objects orbiting our sun, the Kuiper belt is the ‘third zone’ of the solar system (rocky planets like Earth and Mars are in the first zone, while gas giants like Jupiter inhabit the second). It could uncover secrets about the early formation of the solar system.
IAU
In 2006, the International Astronomical Union voted to create a new planetary classification of ‘dwarf planets’: Ceres, Pluto, Haumea, Makemake, and Eris. To be a full planet, an object must orbit the sun, have a spherical shape, and have cleared its orbit of other objects.

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