Jonathan Amos
Science correspondent, BBC News

New Horizons passed the "one million miles to go” mark in the early hours of Monday (GMT). It’s now under one million km from Pluto, for those of you like me who only really understand “new money”. 

And the clock will run down very rapidly as New Horizons sweeps towards the Pluto system at 14km/s. Closest approach is set for 11:50 GMT (12:50 BST; 07:50 EDT) on Tuesday. 

I wanted to share this mosaic that has been assembled by astro-photographer Damian Peach. It shows the growing disc of Pluto as New Horizons has got closer and closer in recent days.  

Image source, NASA/JHU-APL/SWRI – DAMIAN PEACH

The face that is third from the right is the one that the probe will see as it passes just 12,500km above the surface. The best pictures that come back will have a resolution better than 100m per pixel. 

This means you would be able to discern any football stadiums, if they were present on the dwarf planet. There aren’t any; I’m sure of that. But it gives you a sense of what to expect.

We’re not going to see the very highest resolution pictures immediately after flyby. However, the mission team is promising some spectacularly detailed views. 

Watch out also on Tuesday for the last full-frame view of Pluto to be sent to the ground before New Horizons goes into radio silence for its flyby.

This is a "money in the bank” shot that will have been acquired on Monday. It’s an insurance policy in the highly unlikely event that the probe hits a small piece of icy debris during the flyby and is destroyed.

Because of the radio silence from New Horizons during the flyby, we won’t actually have anything new to show on Tuesday itself. So, Nasa will give us Monday’s "money in the bank” shot to tide us over. 

David Shukman
Science editor, BBC News

The steamy heat of a Maryland summer is a surreal setting to wait for news from an icy world on the edge of the solar system. Off the freeway and past the shopping malls, we’re poised for new sights from three billion miles away. It’s vacation time here at Johns Hopkins University but in one corner of an otherwise quiet campus there’s an increasingly excited throng. 

Sometimes when Nasa scientists talk of humanity’s destiny reaching for the stars, it feels uncomfortably over-the-top. But, with this mission, evocative language describing the journey of the robotic New Horizons spacecraft does not seem like hype. We are genuinely on the brink of some major discoveries. Talk of making history, exploring unknown realms, satisfying our eternal curiosity about what lies beyond is not out of place. 

And, for once, bizarrely, there are no real experts. Everyone is a novice when it comes to Pluto and I’m finding people are all asking the same questions for which there are no answers yet. What are the weird-looking features on Pluto’s surface? Will New Horizons survive its flight through a cloud of dust? Does Pluto actually share an atmosphere with its largest moon Charon? 

Hour by hour, we’re all on tenterhooks for images that can only become sharper and more revealing.

Image source, NASA/JHUAPL/SWRI

New Horizons just zipped within one million km of Pluto.

It will cover that distance in less than 20 hours and shoot past the dwarf planet just 12,500km from its surface.

Fly, little probe, fly!

Image source, SPL

You can check its exact progress here:

http://pluto.jhuapl.edu/, external

The briefing is over but the work is just beginning for New Horizons.

The team will hear from the little probe once this afternoon and one final time overnight, before it barrels silently past Pluto tomorrow.

That crucial overnight downlink, called "E-Health 1", is due at 04:15 BST. It will include the last pre-flyby picture of Pluto. 

At less than 4km per pixel, it will (again) be our clearest ever view of the dwarf planet. Hopefully the team will show it to us tomorrow, as we celebrate the flyby taking place.

Principal investigator Alan Stern told the briefing room there was "a tremendous energy" on the New Horizons team at the moment.

For eight years - ever since it swung past Jupiter - the probe has been traversing empty space. It crossed the orbits of Uranus and Neptune when they were on the other side of the Solar System. 

Image source, NASA

Dr Cathy Olkin, one of the New Horizons co-investigators, said that when the craft zooms past tomorrow it will be close enough for its cameras to pick out surprisingly small features.

Pluto is slightly bigger than expected, the mission's principal investigator just explained: 2,370km wide (give or take 20km)

That puts it just ahead of the other far-flung dwarf planet Eris.

Stern also said that Pluto definitely has ice caps - consisting of frozen nitrogen and methane.

Click on the "live coverage" tab above to tune in to Nasa TV and hear the latest from the New Horizons team.

Dr Paul Shenk, a mission scientist from the Lunar Planetary Institute, has been speaking to journalists, who have tweeted some of his comments. 

He is also reported as saying that:

• the dark, twisting lines seen in the new Pluto pictures could be eroded craters or fracture lines, but nobody is certain
• the absence of very big craters suggests the surface might be very "young"
• eventually, the New Horizons data will be able to reveal hills as small as 100m

Sometimes when there's no studio available, a blanket has to do!

Some brand new images have been uploaded to the mission page on the website of Johns Hopkins University Applied Physics Laboratory.

They show both Pluto and Charon from a distance of about three million km; they were snapped late on Saturday evening and downlinked from New Horizons just last night.

Taken in black-and-white by the LORRI camera, they will help the team to make any final navigational adjustments - as well as offering yet another best-ever view of the dwarf planet!

Image source, NASA/JHU-APL/SWRI

Image source, NASA/JHU-APL/SWRI

You can see the full set here - the first five images are new:

http://pluto.jhuapl.edu/soc/Pluto-Encounter/index.php, external

Nasa TV will be streaming live briefings at the important stages over the next couple of days. 

You will be able to watch the key broadcasts right here on this page! These will be as follows, in British Summer Time:

• Monday 15:30 - briefing on mission status and what to expect
• Tuesday 12:30 - countdown to "closest approach"
• Tuesday 13:00 - briefing and release of final pre-flyby image
• Wednesday 01:30 - waiting for New Horizons to "phone home" 
• Wednesday 02:30 - briefing on mission status

It's worth remembering that throughout Tuesday, we won't hear anything from New Horizons itself - it'll be too busy taking pictures and measurements.

In a container bolted to the side of New Horizons, there is a portion of the ashes of Clyde Tombaugh, who first discovered Pluto in 1930.

Image source, AP

In this video, some of Tombaugh's relatives talk to Nasa about his legacy.  

The BBC has a team of experts at the operations centre, at Johns Hopkins University in Baltimore, ready to give you the latest.

Sky at Night presenter Dr Chris Lintott is among them, and already getting excited...

Hello! In almost exactly 24 hours' time, Nasa's New Horizons spacecraft is due to hurtle past Pluto. 

On this page we'll keep you up-to-date with all the latest developments.

It's the culmination of a 10-year, five-billion-km journey, so you won't want to miss it!

Image source, NASA