It was incredibly exciting to see #Perserverence landing safely on Mars. But what does it feel like down there? With no atmosphere or magnetic field, #Mars is bombarded by cosmic radiation and solar winds. A thread on some research published today https://science.sciencemag.org/content/371/6531/811 [1/10]

The surface of Mars currently has radiation levels 2-3 times higher than Earth, which poses a serious headache for manned space missions. But, Mars hasn’t always been this way… [2/10]

It's thought that up to around 4.2 billion years ago, Mars did in fact have a magnetic field, much like Earth’s. Due to either an asteroid impact, or cooling of the molten core, the protective magnetic field disappeared, and the atmosphere was slowly stripped away. [3/10]

But it's not just Mars that has experienced changes in its magnetic field. Earth has too, and though quite not as dramatic, the impacts on life on Earth were enormous. [4/10]

In research just published today in @ScienceMagazine, we find that a flip in the Earth's magnetic poles caused a drop in the magnetic field 42 thousand years ago, weakening the protection against solar flares and cosmic rays. @UNSWScience [5/10]

We show that this caused extreme climate and environmental changes that likely played a role in the extinction of megafauna and possibly even the demise of the Neanderthals. Intense light displays of the aurora would have been visible across much of the globe. [6/10]

The Earth isn’t about to lose its magnetosphere and atmosphere any time soon – but if a similar event happened today, the consequences would be huge: global damage to power grids, satellites, and extreme climate and environmental impacts. [7/10]

To find out more about this research, check out our article in the @ConversationEDU https://theconversation.com/earths-magnetic-field-broke-down-42-000-years-ago-and-caused-massive-sudden-climate-change-155580

We even have a rather awesome movie narrated by the one and only @StephenFry. Just like in The Hitchhiker’s Guide to the Galaxy, the answer comes back to 42. [9/10].

This was a massive team effort – thanks to co-lead author @IntrepidProf and everyone else that made it happen! @DLorrey @Dr_IsoTony @jmwilmshurst @ChronosUnsw @unswbees @Intrepid_Sci and many, many more! [10/10].