The Critics Accuse The Quran of Contradiction Concerning The Length Of A Day.
The critic says:
‘Sura 22:47 and 32:5 tell us that one day to Allah actually means 1,000 years, but Sura 70:4 says a day with Allah is 50,000 years’ 
An unlearned individual may read the critic’s claim and feel it is a genuine contradiction. However closer scrutiny shows there is no contradiction and this claim is only borne out of the critic’s own misunderstanding of the text.
The Arabic word for day is ‘yawm’. Now this can be translated as a day, long period or epoch. As we see from the context the translation would either be long period or epoch as the verses are not referring to 24 hour periods (i.e. the conventional day). As the meaning is not a 24 hour day we realise that their is no contradiction as the term "yawm" can refer to many periods of time all with differing lengths of time. So please keep this in mind when reading this article. To be thorough we shall go into depth concerning their claim
As we further investigate we realise the reason why the length of these long periods or epochs are different (either 1,000 years or 50,000 years) is due to the verses referring to different events. In order to highlight this it is necessary to look at each of the verses individually:
22:47 - And they ask you to hasten on the torment! And Allâh fails not His Promise. And verily, a day with your Lord is as a thousand years of what you reckon. 
Tafsir Jalalayn tells us the day (long period/epoch) referred to in 22:47 is concerning a day in the Hereafter (in Hell) . So we note that this verse is teaching us that the length of a regular day in Hell is equivalent to a thousand years.
32:5 - He arranges (every) affair from the heavens to the earth, then it (affair) will go up to Him, in one Day, the space whereof is a thousand years of your reckoning (i.e. reckoning of our present world's time) 
Tafsir Jalalayn teaches us the Quranic verse 32:5 is referring to a day (long period/epoch) which is equivalent to a thousand years is referring to the affairs taking a day to go up to Allah . This takes a thousand years of our (human) measure and it is described as a yawm (day, long period or epoch).
70:4 - The angels and the Rûh [Jibrael (Gabriel)] ascend to Him in a Day the measure whereof is fifty thousand years, 
Tafsir Jalalayn tells us this is concerning the Day of Resurrection , though this can also be obviously discerned by reading the verses by prior and after the verse in question (70:4). So essentially we realise that this verse tells us the Day of Resurrection is measured as 50,000 (fifty thousand) years. Tafsir Jalalayn does go further and mention it is of the perspective of the disbeliever; hence the Day will be different for the disbeliever (longer) and the believer (shorter). But for the purposes of this article it is sufficient to know this verse of the Quran (70:4) concerns the Day of Resurrection and is referring to a different event (not the same events mentioned in the two previous verses, 22:47 and 32:5)
Thus we realise the Quran speaks of three different events which last a specific amount of time (days):
1. Verse 22:47 concerns a day in the Hereafter (i.e. Hell) which lasts 1,000 years.
2. Verse 32:5 concerns the length of time (a day/long period/epoch) for the affairs to go up to Allah which consists of 1,000 earth years.
3. Verse 70:4 concerns the Day of Judgement which lasts 50,000 earth years for the disbeliever.
All three of these events all take a set amount of time. Two of them take 1,000 years of our reckoning while the last one takes 50,000 years of our reckoning.
So to summarise we can say there is no contradiction as the Quran is not speaking of the same event in each verse. Therefore we realise there is no contradiction at all.
The critic due to his/her lack of research conflates and confuses the three events into one and erroneously believes the three are all the same. This error on the part of the critics leads to their egregious and unscholarly claim which highlights the ignorance on the part of the critic.
May Allah guide us all. Ameen
And certainly Allah knows best.
 Anatomy of the Quran by G.J.O Moshay Chick Productions 2007 pg 117
 Translation and explanation of The Noble Quran In the English Language, A Summarized Version of At-Tabari, Al-Qurtubi and Ibn Kathir with comments from Sahih Al-Bukhari By Dr. Muhammad Taqi-ud-Din Al-Hilali, Ph.D. and Dr. Muhammad Muhsin Khan. Verse 22:47
 Ibid. Verse 32:5
 Ibid. Verse 70:4
 Tafsir al-Jalalayn, trans. Feras Hamza. Royal Aal al-Bayt Institute for Islamic Thought, Amman, Jordan. 2008. Concerning verse 22:47
 Ibid. Concerning verse 32:5
 Ibid. Concerning verse 70:4